Question

3. A Scooter of mass 80 kg is moving with a velocity of 108 km/hr. The force required to
stop the vehicle in 10 sec is
(a) 360 N
(b) 720 N
(c) 180 N
(d) none of these​

Answer 1

Answer :

• d) None of the above

Given :

• Mass (m) = 80 kg
• Initial Velocity (u) = 108 km/hr
• Time (t) = 10 s

To find :

• Force required to stop the body

Solution :

• F = ma

We are given with mass but we need to first find the acceleration .

• Since the body has to stop , the final velocity = 0 m/s.

Initial velocity = 108 km/ hr

= 108 × 5/18

= 6 × 5

= 30 m/s

Hence by the formula of acceleration

$\boxed{\tt a = \dfrac{v - u}{t}}$

= 0 - 30 / 10

= -30 / 10

= -3

Force = mass × acceleration

= 80 × -3

= - 240 N

Here the negetive sign means that the force is done against the motion i.e. a stopping force is applied . If we only take the magnitude ,

Force = 240 N