Question

A toy car of mass $500g$ travels with a uniform velocity of $25cm$ $s^{-1}$ for $5s$. The brakes are then applied and the car is uniformly retarded and comes to rest in further $10s$. Calculate the retardation.

• A. $25m{s}^{-2}$
• B. $0.025m{s}^{-2}$
• C. $25cm{s}^{-2}$
• D. $25km{s}^{-2}$

Answer 1

The correct option is B $0.025m{s}^{-2}$

Given that this toy car has a velocity of 25 cm/sec which is also equal to 0.25 m/sec. Here toy car is retarded confirming it has final velocity 0 m/sec and it came to rest within 10 seconds. We know that acceleration is nothing but rate of change of velocity.
$a=(v-u)/t$
$a=(0-0.25)/10$
$a=-0.025m/s^2$.