Question : A car is travelling at 72 kmh−1 and is 20 m from a barrier when the driver puts on the brakes. The car hits the barrier 2s later. What is the magnitude of the constant deceleration?
(A) 7.2ms^{-2}
(B) 10ms^{-2}
(C) 36ms^{-2}
(D) 15ms^{-2}
Answer : option (B)
Solution :
