Question

A toy car of mass 0.15kg accelerates from a speed of 10 cm/s to a speed of 15 cm/s. What is the impulse acting on the car?

A. 7.5 mN s
B. 37.5 mN s
C. 0.75 N s
D. 3.75 N s


If you could explain how you got it I would appreciate that

Answer 1

v=v2-v1=15-10=5 cm/s

p=mv=0.15•5=0.75 kg•cm/s

Answer 2

Answer : The correct option is, (A) 7.5 mN.s

Explanation :

Impulse : It is defined as the force applied to an object for a certain amount of time.

Formula used :

`I=F* \Delta t`

As we know that:

`F=m* \Delta a\\\\\Delta a=(\Delta v)/(\Delta t)`

Thus, formula of impulse will be:

`I=m* \Delta v`

where,

I = impulse = ?

m = mass = 0.15 kg

`\Delta v` = change in speed of velocity =
`v_(final)-v_(initial)=15cm/s-10cm/s=5cm/s=0.05m/s` (1 m = 100 cm)

Now put all the given values in the above formula, we get:

`I=(0.15kg)* (0.05m/s)`

`I=0.0075kg.m/s=0.0075N.s=7.5mN.s` (1 N.s = 1000 mN.s)

Therefore, the impulse acting on the car is, 7.5 mN.s