Question

The velocity of a body of mass 10 kg changes from 108 km/h to 10 m/s in 4 s on applying a force. The force applied on the body is:

• A. 50 N
• B. -50 N
• C. 200 N
• D. -200N

Answer 1

Answer:

B. -50 N

To calculate the force applied on the body, we need to use the concept of acceleration and Newton's second law of motion.

Initial Velocity:

First, we need to convert the initial velocity from km/h to m/s:

108 km/h = 108 × (1000/3600) m/s = 30 m/s

Change in Velocity:

The change in velocity (Δv) is:

Δv = final velocity - initial velocity
= 10 m/s - 30 m/s
= -20 m/s

Acceleration:

The acceleration (a) can be calculated using the formula:

a = Δv / Δt
= -20 m/s / 4 s
= -5 m/s²

Force Applied:

Now, we can use Newton's second law of motion to calculate the force applied:

F = m × a
= 10 kg × -5 m/s²
= -50 N