GCSE equations of motion Questions (higher only) Equation Comment v = u + at Acceleration is change in velocity ÷ time s = ½ (v+u) × t Average velocity is ½ (v+u) s = ut + ½ at² No 'v' needed v² - u² = 2as No 't' needed Don’t forget units too! Speed (m/s) Time (s) Distance (m) Acceleration (m/s2) We often call these the suvat equations, with: initial velocity u, final velocity v, acceleration a, displacement s, time t. You will be given these in an exam For the following equations, identify u, v, s, a and t, and solve. 1. A particle is accelerated uniformly from rest, so that after 10 seconds it has achieved a speed of 15 m/s. Find its acceleration. u= v= t= equation to use: a= 2. A car accelerates uniformly from rest and reaches 12m/s after covering 40m.. What is its acceleration? u= v= s= equation to use: a= 3. A car accelerates uniformly from 5m/s to 15m/s taking 7.5 seconds. How far did it travel during this period? u= v= t= equation to use: s= 4. A particle is accelerated from 1m/s to 5m/s over a distance of 15m. Find the acceleration. u= v= s= equation to use: a= 5. A train starts from rest and accelerates uniformly at 1.5m/s2 until it attains a speed of 30m/s. Find the time taken and the distance travelled. u= v= a= equation to use: t= s= 6. A train travels along a straight piece of track between 2 stations A and B. The train starts from rest at A and accelerates at 1.25m/s2 until it reaches a speed of 20m/s. Find the distance from A to B u= v= a= equation to use: s= 7. A train is uniformly decelerated from 35m/s to 21m/s over a distance of 350m. Calculate the deceleration. u= v= s= equation to use: a= Answers 1. A particle is accelerated uniformly from rest, so that after 10 seconds it has achieved a speed of 15 m/s. Find its acceleration. u = 0 m/s v =15m/s t = 10 equation to use: v = u + at a= (v-u)÷t a = (15-0)÷10 = 1.5m/s2 2. A car accelerates uniformly from rest and reaches 12m/s after covering 40m. What is its acceleration? u = 0m/s v = 12m/s s = 40m equation to use: v² - u² = 2as (v² - u²) ÷ (2 x s) = a a = 122 ÷ (2x40) = 144 ÷ 80 = 1.8m/s2 3. A car accelerates uniformly from 5m/s to 15m/s taking 7.5 seconds. How far did it travel during this period? u = 5m/s v = 15m/s t = 7.5s equation to use: s = ½ (v+u) × t s = 0.5 (5+15) x 7.5 = 75m 4. A particle is accelerated from 1m/s to 5m/s over a distance of 15m. Find the acceleration. u =1m/s v =5m/s s =15m equation to use: v² - u² = 2as (v² - u²) ÷ (2 x s) = a a = (52 - 12) ÷ (2 x 15) = 24 ÷ 30 = 0.8 m/s2 5. A train starts from rest and accelerates uniformly at 1.5m/s2 until it attains a speed of 30m/s. Find the time taken and the distance travelled. u = 0m/s v = 30m/s a = 1.5m/s2 equation to use: v² - u² = 2as (v² - u²) ÷ (2 x a) = s s = 302 ÷ (2 x 1.5) = 900 ÷ 3 = 300m v = u + at t= (v-u)÷a t = 30÷1.5= 20s 6. A train travels along a straight piece of track between 2 stations A and B. The train starts from rest at A and accelerates at 1.25m/s2 until it reaches a speed of 20m/s. Find the distance from A to B u = 0m/s v = 20m/s a = 1.25m/s2 equation to use: v² - u² = 2as (v² - u²) ÷ (2 x a) = s s = 202 ÷ (2 x 1.25) = 160m 7. A train is uniformly decelerated from 35m/s to 21m/s over a distance of 350m. Calculate the deceleration. u = 35m/s v = 21m/s s = 350m equation to use: v² - u² = 2as (v² - u²) ÷ (2 x s) = a a = (212 - 352) ÷ (2 x 350) = (441-1225)÷700 = -784÷700 = -1.12/s2