Question

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

Answer 1

Force acting = 10N

mass of the body = 2 kg

Time = 3 seconds

$\rule{200}{2}$

F =Ma

10 = 2*a

a = 5 metre per second square

$\rule{200}{2}$

body is intially at rest

hence,

u = 0m/sec

a = 5 m/sec^2

t = 3 seconds

We know that :-

V = U + at

V =  0+15

V = 15 m/sec

$\rule{200}{2}$

change in momentum = force *time

change in momentum = 10*3

change in momentum = 30 kg m/sec

$\rule{200}{2}$

Answer 2

$\huge\bold\red{QUESTION}$

A force of 10 N acts on a body of mass 2 kg for 3 sec, initially at rest. Calculate:-

(i) the velocity acquired by the body

(ii) change in momentum of the body

$\huge\bold\purple{ANSWER}$

Force (f)= 10N

Mass (m) = 2 kg

Initial Velocity (u)= 0 m/s

Time (t) = 3 second

1) $\bold{To \: Find \: The \: Final \: Velocity (v)}$

$\red{Force= Mass × Acceleration}$

$\bold{10 = 2 ×\: Acceleration}$

$Acceleration= \frac{10}{2}$

Acceleration= 5 m/s²

Now,

$Acceleration= \frac{v - u}{t}$

$Acceleration= \frac{v - 0}{3}$

$5 = \frac{v}{3}$

$v = 5 \times 3$

$\bold{v = 15 \: m/s}$

2) $\bold{To \: Find \: The \: Momentum}$

$\red{Momentum (p) = Mass \:(m) ×\: Velocity (v)}$

$\bold{Momentum= 2 \: × 15 }$

$\bold{Momentum= 30 kg \:m/s}$