Question

Momentum of a body increases from 20 kgm/s to 40 kgm/s in 5 second, then the force applied is

(a) 4 N

(b) - 4N

(c) 12 N

(d) - 12 N​

Answer 1

Given:-

• initial momentum = 20 kgm/s
• final momentum = 40 kgm/s
• time = 5 seconds

To find:-

• Force applied to this body

Formula:-

$\underline\red{\boxed{\bf Force = \dfrac{mv-mu}{t}}}$

here, mv = final momentum

• mu = initial momentum
• t = time

Solution:-

→ $\sf F = \dfrac{40-20}{5}$

→ $\sf F = \dfrac{20}{5}$

→ $\sf F = 4 N$

hence, the required answer is 4 N i.e (a) option

________________________________

Momentum:-

• the momentum of an object is equal to the mass of the object times the velocity of the object.
• momentum = mass × velocity
• rate of change in momentum leads to force which is :-

$\underline\red{\boxed{\bf Force = \dfrac{final\:momentum(mv)-initial\:momentum(mu)}{time(t)}}}$

• it's SI unit is kgm/s

ALWAYS KEEP AN EYE OVER THE UNITS