Question

Calculate the change in momentum of a body waiting 5 kg when its velocity decreases from 20 metre per second to 0.20 metre per second?

Answer 1

GIVEN :-

• Mass , m = 5 kg.
• Initial velocity , u = 20 m/s.
• Final velocity , v = 0.20 m/s.

TO FIND :-

• Change in momentum.

SOLUTION :-

$\\ : \implies \displaystyle \sf \: Change \: in \: momentum \ (\Delta p) = mv - mu$

$\\ : \implies \displaystyle \sf \: Change \: in \: momentum \ (\Delta p) = m(v - u) \ \: \: \: \: \: \: \: \: \: \: \: \bigg \lgroup common\bigg \rgroup$

$\\ : \implies \displaystyle \sf \: Change \: in \: momentum \ (\Delta p) = 5(0.20 - 20)$

$\\ : \implies \displaystyle \sf \: Change \: in \: momentum \ (\Delta p) = 1 - 100$

$\\ : \implies \underline{ \boxed{\displaystyle \sf \: Change \: in \: momentum \ (\Delta p) = - 99 \: kg \: ms^{ - 1} }}$

$\therefore \underline {\displaystyle \sf change \: in \: momentum \: of \: a \: body \: is \: -99 kg \: m/s.}$

Answer 2

Given:

• Mass, m = 5kg
• Initial Velocity, u = 20m/s
• Final Velocity, v = 0.20m/s

Find:

Change In Momentum

Solution:

we, know that

$\underline{\boxed{\pink{\sf \triangle p = m(v - u) }}}$

where,

• m = 5kg
• v = 0.20m/s
• u = 20m/s

So,

$\sf \to \triangle p = m(v - u)$

$\sf\to \triangle p = 5(0.20 - 20)$

$\sf\to \triangle p = 5( - 19.8)$

$\underline{\boxed{\blue{\sf\to \triangle p = - 99kg \: m/s }}}$

Hence, change in momentum will be -99kg m/s

The - ve sign indicates that there is a decrease in the momentum of the object.