Projectile motionEdexcel A-Level Physics: Subtopic test

1. 1
   A stone is thrown horizontally at 12 m s⁻¹ from the top of a vertical cliff 45 m high, over the sea. Air resistance may be ignored.

   (a)

   Which statement describes the horizontal velocity of the stone while it is in flight?

   [1 mark]

   • AIt stays at 12 m s⁻¹, because no horizontal force acts on it
   • BIt increases, because gravity accelerates the stone
   • CIt decreases to zero as the stone falls
   • DIt starts at zero and increases as the stone leaves the cliff

   (b)

   Taking g = 9.81 m s⁻², how long does the stone take to reach the sea?

   [1 mark]

   • A2.1 s
   • B3.8 s
   • C3.0 s
   • D9.2 s

   (c)

   Calculate the speed of the stone as it reaches the sea.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A footballer kicks a ball from level ground at 20 m s⁻¹ at 30° above the horizontal. Air resistance may be ignored.

   (a)

   What is the initial vertical component of the ball's velocity?

   [1 mark]

   • A17 m s⁻¹
   • B10 m s⁻¹
   • C20 m s⁻¹
   • D40 m s⁻¹

   (b)

   Which statement is true at the highest point of the ball's flight?

   [1 mark]

   • AThe acceleration of the ball is zero
   • BThe horizontal velocity of the ball is zero
   • CThe speed of the ball is zero
   • DThe vertical velocity is zero, the horizontal velocity is still 17 m s⁻¹ and the acceleration is 9.81 m s⁻² downwards

   (c)

   Calculate the time for which the ball is in the air before it returns to the ground.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A rescue aircraft flies horizontally at a constant 60 m s⁻¹ at a height of 180 m. It releases a supply package which falls to the ground. Air resistance may be ignored.

   (a)

   Calculate the time taken for the package to reach the ground.

   [3 marks]

   (b)

   Calculate the horizontal distance travelled by the package while falling, and state where the aircraft is relative to the package at the moment of impact. Explain your answer.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A student launches a small steel ball horizontally from the edge of a bench top 1.00 m above the floor, using a ramp to give different launch speeds. A pressure pad on the floor records where the ball lands.

   (a)

   Explain why the horizontal distance travelled by the ball is directly proportional to its launch speed, and state what the gradient of a graph of distance against launch speed would represent.

   [6 marks]

   (b)

   The ball leaves the bench at 2.5 m s⁻¹. Calculate the speed of the ball just before it hits the floor and the angle its path then makes with the horizontal. Evaluate whether air resistance would make the real landing distance greater or less than that predicted by ignoring it.

   [6 marks]

   Total for question 4: 12 marks

End of questions