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Exampro GCSE Physics P2 Fces and their effects Self Study Questions Higher tier Name: Class: Auth: Date: Time: 7 Marks: 7 Comments: Page of 32 Q. (a) The stopping distance of a vehicle is made up of two

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Exampro GCSE Physics P2 Fces and their effects Self Study Questions Higher tier Name: Class: Auth: Date: Time: 7 Marks: 7 Comments: Page of 32 Q. (a) The stopping distance of a vehicle is made up of two parts, the thinking distance and the braking distance. (i) What is meant by thinking distance? () (ii) State two facts that affect thinking distance. 2 (2) (b) A car is travelling at a speed of 20 m/s when the driver applies the brakes. The car decelerates at a constant rate and stops. (i) The mass of the car and driver is 600 kg. Calculate the kinetic energy of the car and driver befe the brakes are applied. Use the crect equation from the Physics Equations Sheet. Kinetic energy =... J (2) (ii) How much wk is done by the braking fce to stop the car and driver? Wk done =... J () Page 2 of 32 (iii) The braking fce used to stop the car and driver was 8000 N. Calculate the braking distance of the car. Use the crect equation from the Physics Equations Sheet. Braking distance =... m (2) (iv) The braking distance of a car depends on the speed of the car and the braking fce applied. State one other fact that affects braking distance. () (v) Applying the brakes of the car causes the temperature of the brakes to increase. Explain why. (2) (c) Hybrid cars have an electric engine and a petrol engine. This type of car is often fitted with a regenerative braking system. A regenerative braking system not only slows a car down but at the same time causes a generat to charge the car s battery. State and explain the benefit of a hybrid car being fitted with a regenerative braking system. (3) (Total 4 marks) Page 3 of 32 Q2. (a) Some students have designed and built an electric-powered go-kart. After testing, the students decided to make changes to the design of their go-kart. The go-kart always had the same mass and used the same mot. The change in shape from the first design (X) to the final design (Y) will affect the top speed of the go-kart. Explain why. (3) Page 4 of 32 (b) The final design go-kart, Y, is entered into a race. The graph shows how the velocity of the go-kart changes during the first 40 seconds of the race. Time in seconds (i) Use the graph to calculate the acceleration of the go-kart between points J and K. Give your answer to two significant figures. Acceleration =... m/s 2 (2) (ii) Use the graph to calculate the distance the go-kart travels between points J and K. Distance =... m (2) (iii) What causes most of the resistive fces acting on the go-kart? () (Total 8 marks) Page 5 of 32 Q3. The graph shows the speed of a runner during an indo 60 metres race. (a) Calculate the acceleration of the runner during the first four seconds. (Show your wking.) (3) (b) How far does the runner travel during the first four seconds? (Show your wking.) (3) (c) At the finish, a thick wall of rubber foam slows the runner down at a rate of 25 m/s 2. The runner has a mass of 75kg. Calculate the average fce of the rubber foam on the runner. (Show your wking.) Answer... newtons (N) (2) (Total 8 marks) Page 6 of 32 Q4. When a gun is fired, a very large fce acts on the bullet f a very sht time. The change in momentum of the bullet is given by the following relationship: fce (N) time(s) = change in momentum (kg m/s) (a) An average fce of 4000 newton acts f 0.0 seconds on a bullet of mass 50g. Calculate the speed of the bullet. (Show your wking.) Answer... m/s (4) (b) The bullet is fired hizontally. In the sht time it takes f the bullet to reach its target, its hizontal speed has fallen to 80% of its initial speed. (i) Explain why the speed of the bullet decreases so quickly (2) (ii) Calculate the percentage of its iginal kinetic energy the bullet still has when it reaches its target. (Show your wking.) (4) (Total 0 marks) Page 7 of 32 Q5. A driver is driving along a road at 30 m/s. The driver suddenly sees a large truck parked across the road and reacts to the situation by applying the brakes so that a constant braking fce stops the car. The reaction time of the driver is 0.67 seconds, it then takes another 5 seconds f the brakes to bring the car to rest. (a) Using the data above, draw a speed-time graph to show the speed of the car from the instant the truck was seen by the driver until the car stopped. (5) (b) Calculate the acceleration of the car whilst the brakes are applied Answer =... m/s 2 (3) Page 8 of 32 (c) The mass of the car is 500 kg. Calculate the braking fce applied to the car Answer =... N (3) (d) The diagrams below show what would happen to a driver in a car crash. (i) Explain why the driver tends to be thrown towards the windscreen (ii) During the collision the front end of the car becomes crumpled and buckled. Use this infmation to explain why such a collision is described as inelastic..... (iii) The car was travelling at 30 m/s immediately befe the crash. Calculate the energy which has to be dissipated as the front of the car crumples (8) (Total 9 marks) Page 9 of 32 Q6. A racing driver is driving his car along a straight and level road as shown in the diagram below. (a) The driver pushes the accelerat pedal as far down as possible. The car does not accelerate above a certain maximum speed. Explain the reasons f this in terms of the fces acting on the car (4) (b) The racing car has a mass of 250 kg. When the brake pedal is pushed down a constant braking fce of N is exerted on the car. (i) Calculate the acceleration of the car (ii) Calculate the kinetic energy of the car when it is travelling at a speed of 48 m/s Page 0 of 32 (iii) When the brakes are applied with a constant fce of N the car travels a distance of 44 m befe it stops. Calculate the wk done in stopping the car (2) (Total 6 marks) Q7. (a) The graphs show how the velocity of two cars, A and B, change from the moment the car drivers see an obstacle blocking the road. Time in seconds Time in seconds One of the car drivers has been drinking alcohol. The other driver is wide awake and alert. (i) How does a comparison of the two graphs suggest that the driver of car B is the one who has been drinking alcohol? () (ii) How do the graphs show that the two cars have the same deceleration? () Page of 32 (iii) Use the graphs to calculate how much further car B travels befe stopping compared to car A. Show clearly how you wk out your answer. Additional stopping distance =... m (3) (b) In a crash-test labaty, scientists use senss to measure the fces exerted in collisions. The graphs show how the electrical resistance of 3 experimental types of sens, X, Y, and Z, change with the fce applied to the sens. Which of the senss, X, Y Z, would be the best one to use as a fce sens?... Give a reason f your answer. (2) (Total 7 marks) Page 2 of 32 Q8. The miners wking in a salt mine use smooth wooden slides to move quickly from one level to another. (a) A miner of mass 90 kg travels down the slide. Calculate the change in gravitational potential energy of the miner when he moves 5 m vertically downwards. gravitational field strength = 0 N/kg Use the crect equation from the Physics Equations Sheet. Show clearly how you wk out your answer. Change in gravitational potential energy =... J (2) (b) Calculate the maximum possible speed that the miner could reach at the bottom of the slide. Use the crect equation from the Physics Equations Sheet. Show clearly how you wk out your answer. Give your answer to an appropriate number of significant figures. Maximum possible speed =... m/s (3) Page 3 of 32 (c) The speed of the miner at the bottom of the slide is much less than the calculated maximum possible speed. Explain why. (3) (Total 8 marks) Q9. A car is driven along a straight, snow covered, road. The graph shows how the velocity of the car changes from the moment the driver sees a very slow moving queue of traffic ahead. (a) Use the graph to calculate the distance the car travels while it is slowing down. Show clearly how you wk out your answer. Distance =... m (3) Page 4 of 32 (b) The car has a mass of 200 kg. Calculate the kinetic of the car when it travels at a speed of 2 m/s. Write down the equation you use, and then show clearly how you wk out your answer. Kinetic energy =... J (2) (Total 5 marks) Page 5 of 32 Q0. The diagram shows the velocity-time graph f an object over a 0 second period. (a) Use the graph to calculate the distance travelled by the object in 0 seconds. Show clearly how you wk out your answer. Distance =... m (2) Page 6 of 32 (b) Complete the distance-time graph f the object over the same 0 seconds. (2) (Total 4 marks) Q. The diagram shows the hizontal fces acting on a car of mass 200 kg. Page 7 of 32 (a) Calculate the acceleration of the car at the instant shown in the diagram. Write down the equation you use, and then show clearly how you wk out your answer and give the unit. Acceleration =... (4) (b) Explain why the car reaches a top speed even though the thrust fce remains constant at 3500 N. (3) Page 8 of 32 (c) The diagram shows a car and a van. The two vehicles have the same mass and identical engines. Explain why the top speed of the car is higher than the top speed of the van. (4) (Total marks) Page 9 of 32 Q2. (a) The graphs show how the velocity of two cars, A and B, change from the moment the car drivers see an obstacle blocking the road. Car A Car B One of the car drivers has been drinking alcohol. The other driver is wide awake and alert. (i) How does a comparison of the two graphs suggest that the driver of car B is the one who has been drinking alcohol? () (ii) How do the graphs show that the two cars have the same deceleration? () (iii) Use the graphs to calculate how much further car B travels befe stopping compared to car A. Show clearly how you wk out your answer. Additional stopping distance =... m (3) Page 20 of 32 (b) In a crash test labaty, scientists use senss to measure the fces exerted in collisions. The graphs show how the electrical resistance of 3 experimental types of sens, X, Y and Z, change with the fce applied to the sens. Which of the senss, X, Y Z, would be the best one to use as a fce sens?... Give a reason f your answer. (2) (Total 7 marks) Page 2 of 32 M. (a) (i) distance vehicle travels during driver s reaction time accept distance vehicle travels while driver reacts (ii) any two from: tiredness (drinking) alcohol (taking) drugs speed age accept as an alternative fact distractions, eg using a mobile phone 2 (b) (i) allow mark f crect substitution, ie subsequent step shown provided no 2 (ii) their (b)(i) (iii) 40 crectly calculated allow mark f statement wk done = KE lost allow mark f crect substitution, ie 8000 distance = their (b)(ii) 2 (iv) any one from: icy / wet roads accept weather conditions (wn) tyres road surface mass (of car and passengers) accept number of passengers (efficiency / condition of the) brakes Page 22 of 32 (v) (wk done by) friction (between brakes and wheel) do not accept friction between road and tyres / wheels (causes) decrease in KE and increase in thermal energy accept heat f thermal energy accept KE transferred to thermal energy (c) the battery needs recharging less often accept car f battery increases the range of the car accept less demand f other fuels lower emissions lower fuel costs environmentally friendly is insufficient as the efficiency of the car is increased accept it is energy efficient the decrease in (kinetic) energy / wk done charges the battery (up) accept because not all wk done / (kinetic) energy is wasted [4] M2. (a) me streamlined accept decrease surface area air resistance is smaller (f same speed) accept drag f air resistance friction is insufficient so reaches a higher speed (befe resultant fce is 0) igne reference to mass (b) (i).7 allow mark f crect method, ie allow mark f an answer with me than 2 sig figs that rounds to.7 allow mark f an answer of 7 2 (ii) 7.5 allow mark f crect use of graph, eg Page 23 of 32 (iii) air (resistance) accept wind (resistance) drag is insufficient friction is insufficient [8] M3. (a) acceleration = but 2.5 gains mark do not penalise if both of these present but change in omitted from fmula gains 2 marks unit m/s 2 metres per second squared metres per second per second ms * f mark 3 (b) evidence of using area under graph distance average speed time 0 4 but 20 gains mark gains 2 marks units metres / m 2 * f mark 3 Page 24 of 32 (c) fce = mass acceleration gains mark but 875 gains 2 marks *NB Crect unit to be credited even if numerical answer wrong absent. 2 [8] M4. (a) any evidence of: momentum = mass velocity (wds, symbols numbers) appropriate re-arrangement mass as 0.05kg each gains mark but 800 gains 4 marks 4 (b) (i) any reference to friction with air/air resistance gains mark but idea that friction with air/air resistance is high (at high speed) gains 2 marks 2 (ii) any evidence of: k.e. v 2 k.e. = ½ mv 2 final k.e. initial k.e. either initial final k.e. crectly calculated (i.e. 6000; 0240) each gains mark but (0.8) 2 gains 3 marks but 64%(credit 0.64) gains 4 marks (also credit e.c.f) 4 [0] M5. (a) Each scale optimum Else both half size Straight line joining 30,0 to 30,0.67 to 0, 5.67 any 5 f mark each 5 Page 25 of 32 (b) 6 Else a = 30/5 gets 2 marks Else a = v/t gets mark 3 (c) 9000 Else F = gets 2 marks Else F = ma gets mark 3 (d) (i) Driver has fward momentum Which is conserved Giving drive relative fward speed to car f one mark each 3 (ii) If inelastic ke lost Here ke does wk crumpling car f mark each 2 (iii) Car stops in 75m gets mark W = F.d gets mark W = J OR ke = /2 mv 2 gets mark ke = / ke = J 3 [9] M6. (a) there is a (maximum) fward fce drag/friction/resistance (opposes motion) (not pressure) increases with speed till fward and backward fces equal so no net fce/acceleration any 4 f mark each 4 Page 26 of 32 (b) (i) F = ma = 250a a = 8 m/s 2 f mark each 4 (ii) ke = /2 mv 2 ke = / ke = J f mark each 4 (iii) W = Fd W = W = J f mark each 4 [6] M7. (a) (i) longer reaction time accept slower reactions do not accept slower reaction time unless qualified greater thinking distance accept greater thinking time greater stopping distance accept greater stopping time greater braking distance negates answer (ii) lines / slopes have the same gradient accept slopes are the same velocity decreases to zero in same time / in 2.6 seconds accept any time between 2.4 and 2.8 accept braking distances are the same Page 27 of 32 (iii) 2 accept extracting both reaction times crectly f mark (0.6 and.4) time = 0.8 (s) f mark accept f 2 marks accept calculating the distance travelled by car A as 28.5 m the distance travelled by car B as 40.5 m f 2 marks 3 (b) Z different fce values give a unique / different resistance only sces if Z chosen do not accept fce and resistance are (directly) proptional accept answers in terms of why either X Y would not be best eg X same resistance value is obtained f 2 different fce values Y all fce values give the same resistance [7] M8. (a) (J) allow mark f crect substitution, ie 90 x 0 x 5 provided no subsequent step shown 2 (b) 7 (c) crectly calculated and answer given to 2 3 significant figures accept 7.3 allow 2 marks f an answer with 4 me significant figures, ie 7.32 allow 2 marks f crect substitution, ie 3 500/ their (a) = ½ x 90 x v 2 wk is done allow mark f a statement figures showing KE = GPE 3 (against) friction (between the miner and slide) accept air resistance drag f friction Page 28 of 32 (due to the) slide not (being perfectly) smooth accept miners clothing is rough causing (kinetic) energy to be transferred as heat/internal energy of surroundings accept lost/transfmed f transferred accept air f internal energy of surroundings [8] M9. (a) 35 (m) allow mark f indicating the crect area allow mark f obtaining crect figures from the graph allow mark f calculating area of triangle (25) but omitting the rectangle underneath (2 x 5) 3 (b) allow mark f crect substitution into the crect equation ie / [5] M0. (a) 48 allow f mark crect method shown, ie 6 8 crect area indicated on the graph 2 (b) diagonal line from (0,0) to (6,48) / (6, their (a)) if answer to (a) is greater than 50, scale must be changed to gain this mark hizontal line at 48m between 6 and 0 seconds accept hizontal line drawn at their (a) between 6 and 0 seconds [4] Page 29 of 32 M. (a).25 allow mark f crect resultant fce ie 500N allow 2 marks f crect transfmation and substitution ie allow mark f a crect transfmation but clearly substituting an increct value f fce eg = 3 m/s 2 (b) (c) as speed increases so does the size of the drag fce accept frictional fce / resistive fce / air resistance f drag eventually the drag fce becomes equal to the thrust the resultant fce is now equal to zero and therefe there is no further acceleration the car and van will reach top speed when the fward fce equals the drag fce accept air resistance / frictional / resistive fce f drag fce the drag fce at any speed is smaller f the car than f the van as the car is me streamlined therefe the car s drag fce will equal the fward fce at a higher speed allow converse throughout [] M2. (a) (i) longer reaction time accept slower reactions do not accept slower reaction time unless qualified greater thinking distance accept greater thinking time greater stopping distance accept greater stopping time greater braking distance negates answer Page 30 of 32 (ii) lines / slopes have the same gradient accept slopes are the same velocity decreases to zero in same time / in 2.6 seconds accept any time between 2.3 and 2.8 accept braking distances are the same (iii) 2 accept extracting both reaction times crectly f mark (0.6 and.4 ) time = 0.8(s) f mark accept f 2 marks accept calculating the distance travelled by car A as 28.5 m the distance travelled by car B as 40.5 m f 2 marks 3 (b) Z different fce values give a unique / different resistance only sces if Z chosen do not accept fce andresistance are (directly) proptional accept answers in terms of why either X Y would not be the best eg X same resistance value is obtained f 2 different fce values Y all fce values give the same resistance [7] Page 3 of 32 Page 32 of 32

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