Question

An object experiences force of 4 N acting on it during 4 s and after this force of 6 N in the same direction acting on it during 2 s. What is the magnitude of change of momentum of this object?

a)

28 N*s

b)

16 N*s

c)

12 N*s

d)

20 N*s

Answer 1

First force experienced by the object = F₁ = 4 N

Time period the first force acts on the object for = T₁ = 4 sec

Impulse due to the first force on the object = I₁

I₁ = F₁T₁

I₁ = (4)(4)

I₁ = 16 N.s

Second force experienced by the object = F₂ = 6 N

Time period the second force acts on the object for = T₂ = 2 sec

Impulse due to the second force on the object = I₂

I₂ = F₂T₂

I₂ = (6)(2)

I₂ = 12 N.s

Total impulse on the object due to the two forces = I

I = I₁ + I₂

I = 16 + 12

I = 28 N.s

Change in momentum of the object = P

The change in momentum of the object is equal to the impulse on it due to the forces.

P = I

P = 28 N.s

Magnitude of change in momentum of this object = 28 N.s