Question

The brakes applied to a motor cycle produce a negative acceleration of 5m/s2. If the motor cycle takes 5 seconds to stop after applying brakes. Calculate the distance it covers during this time.

Answer 1

Answer:

62.5 metres

Explanation:

Acceleration = a = -5m/s²

Time = t = 5 seconds

Final velocity = v = 0m/s  (As the motor cycle would stop finally)

First equation of motion says: v=u+at

Substituting the values,

0=u+(-5)5

0=u-25

u= 25 m/s

The initial velocity is 25m/s

The second equation of motion says: $s=ut+\frac{1}{2}at^{2}$

where,

s=distance (unknown)

u= initial velocity = 25m/s

a= acceleration = -5m/s²

t= time = 5 seconds

substituting,

$s=25 \times5+\frac{1}{2} \times (-5) \times(5)^{2}$

$s=125+\frac{1}{2} \times-125$

$s=125-62.5$

s=62.5m

The motor cycle covers a distance of 62.5 metres