DP Physics Questionbank

A ball of mass m strikes a vertical wall with a speed v at an angle of θ to the wall. The ball rebounds at the same speed and angle. What is the change in the magnitude of the momentum of the ball?

A. 2 mv sin θ
B. 2 mv cos θ
C. 2 mv 
D. zero

A stationary nucleus of polonium-210 undergoes alpha decay to form lead-206. The initial speed of the alpha particle is v. What is the speed of the lead-206 nucleus?

A.  $\frac{206}{4}$v

B.  v

C.  $\frac{206}{210}$v

D.  $\frac{4}{206}$v

Explain, with reference to change in momentum, why a flexible safety net is less likely to harm the skier than a rigid barrier.

An object of mass $m$ strikes a vertical wall horizontally at speed $U$. The object rebounds from the wall horizontally at speed $V$.

What is the magnitude of the change in the momentum of the object?

A.  $0$

B.  $m\left(V-U\right)$

C.  $m\left(U-V\right)$

D.  $m\left(U+V\right)$

An object of mass $2m$ moving at velocity $3v$ collides with a stationary object of mass $4m$. The objects stick together after the collision. What is the final speed and the change in total kinetic energy immediately after the collision?

Determine $v$. State your answer to an appropriate number of significant figures.

Determine $v$. State your answer to an appropriate number of significant figures.

When the sledge is moving on the horizontal region of the snow, the girl jumps off the sledge. The girl has no horizontal velocity after the jump. The velocity of the sledge immediately after the girl jumps off is 4.2 m s^–1. The mass of the girl is 55 kg and the mass of the sledge is 5.5 kg. Calculate the speed of the sledge immediately before the girl jumps from it.

The girl chooses to jump so that she lands on loosely-packed snow rather than frozen ice. Outline why she chooses to land on the snow.

Player B intercepts the ball when it is at its peak height. Player B holds a paddle (racket) stationary and vertical. The ball is in contact with the paddle for 0.010 s. Assume the collision is elastic.

Calculate the average force exerted by the ball on the paddle. State your answer to an appropriate number of significant figures.

The player’s foot is in contact with the ball for 55 ms. Calculate the average force that acts on the ball due to the football player.

between B and C.

An object is moving in a straight line. A force F and a resistive force f act on the object along the straight line.

Both forces act for a time t.

What is the rate of change of momentum with time of the object during time t ?

A.     F + f 

B.     F – f

C.     (F + f )t

D.     (F – f )t 

Determine the magnitude of the average resultant force acting on the block between B and C.

between A and B.

A ball of mass m collides with a vertical wall with an initial horizontal speed u and rebounds with a horizontal speed v. The graph shows the variation of the speed of the ball with time.

What is the magnitude of the mean net force on the ball during the collision?

A.     $\frac{m(u-v)}{(t_2+t_1)}$

B.     $\frac{m(u-v)}{(t_2-t_1)}$

C.     $\frac{m(u+v)}{(t_2+t_1)}$

D.     $\frac{m(u+v)}{(t_2-t_1)}$

A second identical ball is placed at the bottom of the bowl and the first ball is displaced so that its height from the horizontal is equal to 8.0 m.

The first ball is released and eventually strikes the second ball. The two balls remain in contact. Determine, in m, the maximum height reached by the two balls.

Determine the average force exerted on the floor by the ball.

A second identical ball is placed at the bottom of the bowl and the first ball is displaced so that its height from the horizontal is equal to 8.0 m.

The first ball is released and eventually strikes the second ball. The two balls remain in contact. Determine, in m, the maximum height reached by the two balls.

Determine the magnitude of the average resultant force acting on the block between B and C.

between A and B.

between B and C.

Determine the initial acceleration of the spacecraft.

The egg comes to rest in a time of 55 ms. Determine the magnitude of the average decelerating force that the ground exerts on the egg.

A ball of mass m collides with a wall and bounces back in a straight line. The ball loses 75 % of the initial energy during the collision. The speed before the collision is v.

What is the magnitude of the impulse on the ball by the wall?

A.   $\left(1-\frac{\sqrt{3}}{2}\right)mv$

B.   $\frac{1}{2}mv$

C.   $\frac{5}{4}mv$

D.   $\frac{3}{2}mv$

Determine the initial acceleration of the spacecraft.

Determine the magnitude of the average decelerating force that the ground exerts on the egg.

Show that the tension in the rope is about 5 kN.

Outline why a force acts on the airboat due to the fan blade.

Show that the tension in the rope is about 5 kN.

Outline why a force acts on the airboat due to the fan blade.

Calculate the average force exerted by the racquet on the ball.

Calculate the average force exerted by the racquet on the ball.

Calculate the speed of the ball as it leaves the racket.

Show that the average force exerted on the ball by the racket is about 50 N.

Calculate the ratio $\frac{\mathrm{kinetic} \mathrm{energy} \mathrm{of} \mathrm{alpha} \mathrm{particle}}{\mathrm{kinetic} \mathrm{energy} \mathrm{of} \mathrm{thorium} \mathrm{nucleus}}$.