P.3.4.1.4 Projectile motion

Two spheres, P and Q, have the same volume but P has a greater mass. The spheres fall in air at their terminal velocities v_P and v_Q respectively.

Which row states the relationship between v_P and v_Q and the reason?

• A

• B

• C

• D

A projectile is launched with a speed of 25 m s^–1 at an angle of 35° to the horizontal, as shown in the diagram.

Air resistance is negligible. What is the time taken for the projectile to return to the ground?

• 1.5 s

• 2.1 s

• 2.9 s

• 4.2 s

Two identical balls, X and Y, are at the same height and a horizontal distance of 25 cm apart.

X is projected horizontally with a velocity of 0.10 m s^–1 towards Y at the same time that Y is released from rest. Both X and Y move freely in the absence of air resistance.

What is the distance between the balls 1.0 s later?

• 0.15 m

• 0.25 m

• 2.4 m

• 4.9 m

The diagram shows the path of a projectile launched from ground level with a speed of 25 m s^–1 at an angle of 42° to the horizontal.

What is the horizontal distance from the starting point of the projectile when it hits the ground?

• 23 m

• 32 m

• 47 m

• 63 m

A stone of mass 0.4 kg is projected horizontally at a speed of 6.0 m s⁻¹ from the top of a wall, 5.0 m above the surrounding ground. When it arrives at the ground its speed is 10 m s⁻¹.

How much energy is lost by the stone in falling through the air?

• 2.4 J

• 6.8 J

• 12.8 J

• 14.4 J

A ball of mass 0.20 kg is thrown and moves in a curved path, as shown below. At Q it is travelling horizontally.

Assume air resistance is negligible. What is the momentum of the ball at Q?

• zero

• 2.0 N s

• 3.5 N s

• 4.0 N s

A ballbearing X of mass 2m is projected vertically upwards with speed u. A ballbearing Y of mass m is projected at 30° to the horizontal with speed 2u at the same time. Air resistance is negligible. Which of the following statements is correct?

• The horizontal component of Y's velocity is u.

• The maximum height reached by Y is half that reached by X

• X and Y reach the ground at the same time.

• X reaches the ground first.

A golf ball was hit from the surface of the Moon. The time of flight was 4.0 s. What is the best estimate for the maximum height reached by the ball?

acceleration due to gravity on the Moon = 1.6 m s^–2

• 3 m

• 15 m

• 40 m

• 80 m

A beam of electrons, moving with a constant velocity v in a vacuum, enters a uniform electric field between two metal plates. Which line, A to D, in the table describes the components of the acceleration of the electrons in the x and y directions as they move through the field?

• acceleration in x direction: zero

  acceleration in y direction: zero

• acceleration in x direction: zero

  acceleration in y direction: constant

• acceleration in x direction: constant

  acceleration in y direction: zero

• acceleration in x direction: constant

  acceleration in y direction: constant

Which line, A to D, in the table correctly describes the trajectory of charged particles which enter separately, at right angles, a uniform electric field, and a uniform magnetic field?

• A

• B

• C

• D