Question

a constant retarding force of 75N is applied to anlbody of mass 30kg moving initialy with a speed of 36kmh'1.calculate the time taken by the body to stop​

Answer 1

Given that, a constant retarding force of 75 N is applied to anlbody of mass 30 kg moving initialy with a speed of 36 km/hr.

We have to find the time taken by the body to stop.

From the above data we have, F = 75N, m = 30 kg, u = 36 km/h and v = 0 m/s.

The product of mass and acceleration is known as Force.

F = ma

Substitute the known values,

→ 75 = 30 × a

→ 75/30 = a

→ 2.5 = a

Therefore, the acceleration of the body is 2.5 m/s².

Now, using the First Equation Of Motion,

v = u + at

Substitute v = 0 m/s, u = 36 km/hr and a = 2.5 m/s².

Before that, convert u into m/s. To do this, multiply the given value by 5/18.

u = 36 × 5/18 = 10 m/s

→ 0 = 10 + 2.5t

→ -10 = 2.5t

→ 4 = t

Therefore, the time taken by the body to stop is 4 sec.