Question

A force changes the velocity of a body of mass 10kg. From 2m/s to 5m/s in 2seconds. Find: (a)The initial momentum of the body (b)The final momentum of the body (c)The force acting which changes its velocity from 2m/s to 5m/s.

Answer 1

(a) initial momentum
p=10*2=20 kg m/s
(b) p=10*5=50 kg m/s
(c) acceleration, a=v-u/t
a=5-2/2=3/2m/sec square
we know,
force=m*a
f=10*3/2=5*3=15 Newton

Answer 2

Solution

Given that a force changes the velocity of a body of mass 10kg. From 2m/s to 5m/s in 2seconds.

We have to find (a)The initial momentum of the body (b)The final momentum of the body (c)The force acting which changes its velocity from 2m/s to 5m/s.

Explanation

Here we have ;

• Mass of body (M) = 10 kg
• Initial velocity (u) = 2 m/s
• Final velocity (v) = 5 m/s
• Time taken (t) = 2 s

a) Initial momentum of body :

→ Initial momentum = m * u

→ Initial momentum = 10 * 2

→ Initial momentum = 20

→ Initial momentum = 20 kg.m/s [Ans : a]

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b) Final momentum of body :

→ Final momentum = m * v

→ Final momentum = 10 * 5

→ Final momentum = 50

→ Final momentum = 50 kg m/s [Ans : b]

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c) Force acting on body :

→ Force = Mass * Acceleration

→ Acceleration = (v - u)/t

→ Force acting = 10 * (5 - 2)/2

→ Force acting = 10 * (3/2)

→ Force acting = 5 * 3

→ Force acting = 15 N [Ans : c]