Question

1. A bob of mass 100 g tied at the end of a string of length 50 cm is revolved in a
Vertical circle with a constant speed of Ims 2. When the tension in the string is 0.7
N, the angle made by the string with the vertical is (g=10ms)
1) 0°
2) 90°
3) 180°
4) 60°​

Answer 1

Answer: Correct option is 4 i.e. 60°

Answer is in the pic and i hope it helps you

Answer 2

Answer:

The angle made by the string with the vertical is 60°.

(4) is correct option.

Explanation:

Given that,

Mass of bob = 100 g

Length = 50 cm

Speed =1 m/s

Tension = 0.7

We need to calculate the angle made by the string with the vertical

Using balance equation

$T-\dfrac{mv^2}{r}=mg\cos\theta$

Put the value into the formula

$0.7-\dfrac{100\times10^{-3}\times1}{50\times10^{-2}}=100\times10^{-3}\times10\cos\theta$

$\cos\theta=\dfrac{0.7-\dfrac{100\times10^{-3}\times1}{50\times10^{-2}}}{100\times10^{-3}\times10}$

$\cos\theta=0.5$

$\theta=\cos^{-1}(0.5)$

$\theta=60^{\circ}$

Hence, The angle made by the string with the vertical is 60°.