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
please help ​

Answer 1

Given :

• Mass (m) of body = 2 kg
• Force (F) acts = 10 N
• Time (t) = 3 seconds
• Initial velocity (u) = 0 ..... [ at rest ]

To find :

• Velocity acquired by the body
• Change in momentum

According to the question,

i)

$\sf \implies{F=ma }$

$\implies \sf{10 = 2 \times a}$

$\implies \sf{a = \cancel\frac{10}{2} = 5 \: m {s}^{2} \orange \bigstar }$

Now we have to find velocity acquires by the body,

By using Newton's first equation of motion,

$\implies\sf{v =u + at }$

$\implies \sf{v = 0 + 5 \times 3}$

$\implies \sf{v = 0 + 15}$

$\implies \sf{15 \: m {s}^{ - 1}\orange\bigstar }$

So,the velocity acquires by the body is 15 m/s...

ii)

Now we will calculate change in momentum

So,the formula is

Change in momentum = Final momentum (mv) - Initial momentum (mu)

$\implies \sf{2 \times 15 - 2 \times 0}$

$\sf \implies{30 - 0}$

$\sf \implies{30 \: kg \: m {s}^{ - 1} \orange \bigstar}$

So,the change in momentum is 30 kg m/s...