Question

A force of 10 N acts on a body of mass 2 kg for
3 s, initially at rest. Calculate : (i) the velocity
er acquired by the body, and (ii) change in momentum
of the body. In 20
1 2
Ans. (i) 15 m s-1, (ii) 30 kg m s-1.
​

Answer 1

velocity

10x3÷2=15

change in momentm

v-u

what is the 2012 i can understand

plz tell and then i will solve surely

Answer 2

Answer :-

Given

•Force applied = 10 N

•Mass of Body = 2 kg

•Time of application of force = 2 sec

(i)

To find out velocity we must find out the acceleration of body .

♦As we know

Force = Mass × Acceleration

→ 10 = 2 × a

→ 10 ÷ 2 = a

→ 5 = a

Or acceleration = 5 m/s²

♦Now as velocity

v = u + at

→ v = 0 + 5(3)

→ v = 15 m/s

(ii)

Change in Momentum :-

**Note as no force is working after 3 sec there will be no increase in velocity after 3rd sec.

Momentum = Mass × velocity

◾Hence :-

▪️Initial momentum = m × u

= 2 × 0

= 0 kg m/s

▪️Final momentum = m × v

= 2 × 15

= 30 kg m/s

Now change in Momentum

= Final momentum - Initial momentum

= 30 - 0

= 30 kg m/s