3.3. Linear momentum and its conservation
A subsection of Physics, 9702, through 3. Dynamics
Listing 10 of 111 questions
A ball Y moves along a horizontal frictionless surface and collides with a ball Z, as illustrated in the views from above in and . Y Z P Q 0.25 kg mZ BEFORE COLLISION P Q 0.25 kg mZ AFTER COLLISION Y Z 27° 44° 3.7 m s–1 5.5 m s–1 (not to scale) (not to scale) Ball Y has a mass of 0.25 kg and initially moves along a line PQ. Ball Z has a mass mZ and is initially stationary. After the collision, ball Y has a final velocity of 3.7 m s–1 at an angle of 27° to line PQ and ball Z has a final velocity of 5.5 m s–1 at an angle of 44° to line PQ. Calculate the component of the final momentum of ball Y in the direction perpendicular to line PQ. component of momentum = N s By considering the component of the final momentum of each ball in the direction perpendicular to line PQ, calculate mZ. mZ = kg During the collision, the average force exerted on Y by Z is FY and the average force exerted on Z by Y is FZ. Compare the magnitudes and directions of FY and FZ. Numerical values are not required. magnitudes: directions: Two blocks, A and B, move directly towards each other along a horizontal frictionless surface, as shown in the view from above in . A B 4 m s–1 6 m s–1 The blocks collide perfectly elastically. Before the collision, block A has a speed of 4 m s–1 and block B has a speed of 6 m s–1. After the collision, block B moves back along its original path with a speed of 2 m s–1. Calculate the speed of block A after the collision. speed = m s–1
9702_w23_qp_22
THEORY
2023
Paper 2, Variant 2
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Define linear momentum. A car of mass 1800 kg is moving in a straight line. shows the variation with time t of the momentum p of the car. t / s p / 104 N s Calculate the maximum speed reached by the car. maximum speed = m s–1 Calculate the maximum kinetic energy of the car. maximum kinetic energy = J Show that the acceleration of the car at time t = 4.0 s is 5.0 m s–2. Determine the distance travelled by the car between times t = 0 and t = 12.0 s. distance = m On , sketch the variation with time t of the acceleration a of the car in from t = 0 to t = 12.0 s. −10 −5 a / m s−2 t / s
9702_w24_qp_21
THEORY
2024
Paper 2, Variant 1
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State the principle of conservation of momentum. A ball X has mass 240 g and moves in a straight line on a horizontal frictionless surface with an initial speed of 16 m s–1. The ball collides with a stationary ball Y that has mass 480 g. After the collision, ball X is stationary, as shown in . ball X, mass 240 g ball Y, mass 480 g 16 m s–1 BEFORE surface ball X, mass 240 g ball Y, mass 480 g v AFTER surface Show that the speed v of ball Y after the collision is 8.0 m s–1. Calculate the change in the total kinetic energy ∆EK of the balls due to the collision. ∆EK = J The collision in lasts for a time of 2.0 ms. Assume that the contact force between the balls is constant during this time. Determine the magnitude and direction of the force exerted on ball X by ball Y during the collision. magnitude = N direction Compare the magnitude and direction of the force exerted on ball Y by ball X during the collision with the answers in . No further calculations are required.
9702_w24_qp_23
THEORY
2024
Paper 2, Variant 3
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Questions Discovered
111