1.6. Momentum
A subsection of Physics, 5054, through 1. Motion, forces and energy
Listing 10 of 14 questions
A small boat travels with a velocity of 4.0 m / s due north in an area of still water. State what is meant by velocity. The boat travels from the area of still water into an area where the velocity of the water is 2.0 m / s towards the north-east, as shown in . VWLOO ZDWHU ƒ ( YHORFLW\RI ERDWLQVWLOO ZDWHU PV YHORFLW\ RIZDWHU PV (not to scale) Combining the initial velocity of the boat with the velocity of the water gives the resultant velocity of the boat. In the space on the page opposite, draw a vector diagram to show the resultant velocity. Use your diagram to find the size and direction of the resultant velocity.
5054_s14_qp_21
THEORY
2014
Paper 2, Variant 1
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In a safety test, a car of mass 1100 kg travels at a speed of 10 m / s and collides with a stationary van of mass 3000 kg. After the collision the car and the van move together with a velocity v. shows the car and van before and after the collision. before collision after collision car mass = 1100 kg velocity = 10 m / s van mass = 3000 kg velocity = 0 m / s velocity = v The total momentum of the car and van is conserved during the collision. Define ‘momentum’. State the unit of momentum. Calculate the velocity v of the car and van after the collision. v = m / s Calculate the total kinetic energy of the car and van after the collision. kinetic energy = J State the transfer of energy that occurs in the collision.
5054_s23_qp_21
THEORY
2023
Paper 2, Variant 1
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shows the speed–time graph for a car travelling on a straight horizontal road. time / s speed m / s Describe the motion of the car shown in . At time t = 10 s the engine of the car is switched off. The brakes are not applied. Name two forces that act on the car to cause the change in motion after t = 10 s. Suggest why is a curve after t = 10 s. Between t = 10 s and t = 20 s the speed of the car changes from 18 m / s to 11 m / s. The mass of the car is 1200 kg. Calculate the change in momentum of the car in this time. Give the unit of your answer momentum change = unit Calculate the average resultant force exerted on the car during this time. average resultant force = N
5054_s23_qp_22
THEORY
2023
Paper 2, Variant 2
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shows two trolleys. On the front of trolley A, there is a wooden rod. Trolley B is initially at rest. As trolley A moves towards the right, the rod enters the modelling clay. Trolley A slows down and trolley B starts moving. The trolleys then stick together and continue moving towards the right. wooden rod modelling clay trolley A trolley B shows the speed−time graph for the two trolleys. 0.2 0.4 0.6 0.8 0.1 0.2 0.3 0.4 0.5 0.6 t / s speed m / s 0.7 0.8 trolley A trolley B trolley A and B The trolleys start to collide at time t = 0.30 s. At t = 0.50 s, the trolleys are moving at the same speed. State how shows that, during the collision, trolley B has a uniform acceleration. Describe how the graph in shows that the magnitude of the acceleration of trolley B is larger than the magnitude of the deceleration of trolley A. Calculate the acceleration of trolley B when t = 0.40 s. acceleration = m / s2 The mass of trolley A = 0.80 kg. The mass of trolley B = 0.60 kg. Show that momentum is conserved in the collision. In another collision between the same trolleys, the rod and modelling clay are not present. Trolley A hits trolley B with the same initial speed. Explain why the force between the trolleys is larger in this collision.
5054_s24_qp_22
THEORY
2024
Paper 2, Variant 2
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A jet ski is a type of boat that carries one or two people and travels at high speed on water. shows a student riding on a jet ski. direction of movement jet ski jet of water A high‑speed jet of water is forced backwards out of the back of the jet ski by a pump inside the jet ski. The pump increases the momentum of the water that is forced backwards out of the back of the jet ski. Complete the word equation to show the relationship between the resultant force on an object and the change in momentum of the object. resultant force = In 2.0 s, the pump increases the backwards speed of 180 kg of water by 30 m / s. Calculate the backwards force exerted on the water. force = N Using Newton’s third law of motion, explain why there is a forwards force on the jet ski. The student has a mass of 70 kg and the jet ski has a mass of 280 kg. Use your answer from to determine the acceleration of the student and jet ski when no resistive forces are acting. acceleration = m / s2 The jet ski reaches a speed of 20 m / s. Calculate the total kinetic energy of the student and jet ski at this speed. kinetic energy = J
5054_w24_qp_22
THEORY
2024
Paper 2, Variant 2
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Questions Discovered
14