Question

A pendulum bob of mass 50 g is suspended with the roof of an elevator .If the lift is falling with a uniform acceleration 5ms-2.find the tension in the string .Take g as 10ms-2

Answer 1

Answer:-

T = 0.75 N

Given:-

m = 50 g

a = 5 m/s²

g = 10 m/s²

To find :-

The tension force in the string.

Solution:-

Since, elevator falling with an acceleration of 5m/s².

Let tension force exerted on Bob be T.

Take Bob as system.

The force exerted on Bob will be:-

1) Tension force in upward direction.

2) Gravitational force downward.

See In the above attachment.

The net force act upon Bob is:-

→$\mathsf{T - mg = F_{net}}$

→$\mathsf{T -mg = m a }$

→$\mathsf{T = ma + mg}$

→$\mathsf{T = m (a +g)}$

Put the given values,

→$\mathsf{ T = \dfrac{50}{1000}\left(5 + 10\right) }$

→$\mathsf{T = \dfrac{1}{20}\times 15}$

→$\mathsf{ T = \dfrac{15}{20}}$

→$\mathsf{T = 0.75 N}$

hence,

Tension force exerted by string on Bob will be 0.75 N.