JEE Main 2022 · 29 June · evening · Single correct · +4 / −1
A small toy starts moving from the position of rest under a constant acceleration. If it travels a distance of 10m in t s, the distance travelled by the toy in the next t s will be :
- (a) 10 m
- (b) 20 m
- (c) 30 m
- (d) 40 m
Answer and solution
Answer (c) 30 m
Solution
Physics sir · 3 steps
From rest, distances in equal time intervals go 1 : 3 : 5, so the next t s covers three times 10 m.
- First t seconds. Starting from rest, s = 1/2at². So 1/2at² = 10 m.
- After 2t seconds. The total distance in time 2t is 1/2a(2t)² = 4 × 1/2at² = 40 m.
sₙₑₓₜ = s(2t) - s(t) = 40 - 10 = 30 m
- So. The toy covers 30 m in the next t seconds, option (c). This matches Galileo's ratio 1 : 3 for the first two equal intervals.
The idea to keep. For motion from rest with constant acceleration, distances in successive equal time intervals are in the ratio 1 : 3 : 5 : 7, the odd numbers.
Answer from the NTA final answer key. Solution by PrepWiser.