Question

A body of mass 10 g is tied to a string of length 0.4 m and it is whirled in a horizontal plane with a speed of 6 m/s. Then the tension in the string is

• A. 1.9 N
• B. 36 N
• C. 0.9 N
• D. 3.6 N

Hint:

For circular motion problems, use the formula for centripetal force \( T = \frac{mv^2}{r} \) to calculate the tension in the string.

Answer 1

The Correct Option is C

The tension in the string can be calculated using the centripetal force formula: \[ T = \frac{mv^2}{r} \] Where: - \( m \) is the mass of the body, - \( v \) is the velocity, - \( r \) is the radius (length of the string). We are given: - Mass, \( m = 10 \, \text{g} = 0.01 \, \text{kg} \), - Velocity, \( v = 6 \, \text{m/s} \), - Radius, \( r = 0.4 \, \text{m} \). Substituting these values into the formula: \[ T = \frac{0.01 \times 6^2}{0.4} = \frac{0.01 \times 36}{0.4} = \frac{0.36}{0.4} = 0.9 \, \text{N} \] Thus, the tension in the string is \( 0.9 \, \text{N} \). \[ \boxed{0.9 \, \text{N}} \]