Motion calculations: including complex ones (a=(v−u)/t, v²−u²=2ax & v=x/t) | Exit Quiz | Oak National Academy

Match the key words or phrases to their definitions.

• the rate of change of displacement over a time period

• the velocity of an object at the end of a time period

• average velocity

• the rate of change of velocity over a time period

• average acceleration

• the velocity of an object at the start of a time period

Answer explanation

Initial refers to the starting velocity and final the finishing velocity. The average velocity is the rate of change of displacement over a time period and average acceleration is the rate of change of velocity over a time period.

A race car increases its velocity from 12 m/s to 48 m/s in a time of 6.0 s. Calculate the acceleration of race car.

• 48 m/s²

• 42 m/s²

• 8.0 m/s²

• 6.0 m/s²

• 288 m/s²

Answer explanation

acceleration = change in velocity ÷ time acceleration = (48 m/s – 12 m/s) ÷ 6.0 s acceleration = 6.0 m/s²

A motorcycle slows with a deceleration of –5.0 m/s² from 25 m/s to a stop. Calculate the distance the motorcycle takes to come to a stop.

• 31.3 m

• 125 m

• 41.7 m

• 83.3 m

• 62.5 m

An aeroplane starting from rest needs to reach a take–off velocity of 60 m/s to take off from a runway of length 1500 m. Calculate the minimum acceleration the airplane will need.

• 0.02 m/s²

• 4.8 m/s²

• 2.4 m/s²

• 1.2 m/s²

• 3.6 m/s²

Answer explanation

$$v² – u² = 2ax$$ $$60² – 0² = 2 × a × 1500$$ $$3600 – 0 = 2 × a × 1500$$ $$3600 = 2 × a × 1500$$ $$a = 3600 ÷ (2 × 1500)$$ $$a = 1.2$$m/s²$$

• 141 m/s

• 158 m/s

• 200 m/s

• 250 m/s

• 300 m/s