Question

A stone of 750 gram moving at 100 m/s strikes a nail. The nail stops the stone in a time of 5 seconds. What is the force of nail on the stone?

(a) -2500N.

(b) 1500N.

(c) 2500N.

(d) -15N

Answer 1

Step-by-step explanation:

Mass of the hammer (m) = 500 g = 0.5 kg

The initial velocity of the hammer (u) = 50 m/s

The nail takes time to stop the hammer (t) = 0.01 s

The velocity of the hammer (v) = 0 (since the hammer finally comes to rest)

From Newton’s second law of motion

f = m (v – u) / t

Where f = force

f = 0.5 × (0 – 50) / 0.01

f = -2500 N

Answer 2

Answer:

Given,

ω=600rad/s

P=1.2kW=1.2×1000=1200W

τ=?

∴Power, P=τω

$∴τ = \frac{p}{ω} = \frac{1200}{600} \\∴ τ=2Nm \: Ans.$