Question

A 0.309 kg pendulum bob passes through the lowest part of its path at a speed of 3.20 m/s. What is the tension in the pendulum cable at this point if the pendulum is 88.7 cm long?

Tries 0/12

When the pendulum reaches its highest point, what angle does the cable make with the vertical?

Tries 0/12

What is the tension in the pendulum cable when the pendulum reaches its highest point?

Answer 1

1)

let the tension at the lowest point is T

now , at the bottom ,

T = mg + mv^2/L

T = 0.309 * ( 9.8 + 3.2^2/0.887)

T = 6.6 N

the tension at the lowest point is 6.6 N

2)

Now , for the height point ,

angle of string with vertical is theta

Using conseravtion of energy

0.5 * m * u^2 = m * g * L * (1 - cos(theta))

0.5 * 3.2^2 = 9.8 * 0.887 * ( 1 - cos(theta))

theta = 65.7 degree

Now , at the highest point

T = mg * cos(theta)

T = 0.309 * 9.8 * cos(65.7)

T = 1.25 N

the tension in the cable at the highest point is 1.25 N