Question

A constant retarding force of 50 newton is applied to a body of mass 20 kg moving initially with a speed of 15 metre per second how long does the body take to stop.

Answer 1

Given:-

•Constant retarding force is 50 Newton.

•Mass of a body is 20 kg.

•Speed of a body is 15 m/s.

To Find:-

•How long the body take to stop?

Solution:-

Given,

• Force= -50N
• Mass = 20kg
• u = 15m/s
• v = 0

We are said to find t = ?

As we know that,

$\: \: \sf \: inital \: linear \: momentum = mu$

Now put the value

$\: \: \sf \: inital \: linear \: momentum = 20 \times 15 \\ \\ \: \: \sf \: inital \: linear \: momentum = 300 \: n.s$

As we know that,

$\: \: \sf \: final \: linear \: momentum = mu$

Now put the value

$\: \: \sf \: final \: linear \: momentum = 20 \times 0 \\ \\ \: \: \sf \: final \: linear \: momentum = 0 \: n.s$

we have,

$\: \: \sf \: f = \frac{mv - mu}{t}$

Now substitute the known values,

$\: \: \sf \: - 50 = \frac{0 - 300}{t} \\ \\ \: \: \sf \: - 50 = \frac{0 - 300}{t} \\ \\ \: \: \sf \: t = 6s$

Hence,time of a body is 6 second.

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