Question

A force of 70N acts on a body at rest for 0.1s and a force of 25N acts for the next 0.2s in opposite
direction. If the final velocity of the body is 5 ms the mass of the body is
a) 1 kg
b) 2 kg
c) 0.8 kg
d) 0.4 kg​

Answer 1

Answer:

plz mark as brainly

d 0.4 kg

Explanation:

Let the mass of the body be m.

Case:1

Force of 25N acts on the body for 0.2s

We know that F=ma

F=ma

F=m[(v-u)/t]

25=m[(v-0)/0.2]

5=mv

v=5/m

This velocity acts as initial velocity for the next case.

Case:2

Force of 70N acts for the next 0.1s in Opposite direction.

Initial velocity=5/m

Final velocity=-5 {negative as because in opposite direction}

Force=-70N

F=ma

-70=m[(-5-5/m)/0.1]

-7=m[-5-5/m]

-7=-5m-5

-2=-5m

m=2/5=0.4Kg

Hence mass of the body is 0.4Kg.