Question 215: Oscillations

Question

A pendulum bob has a speed of 3 m/s at its lowest position. The pendulum is 50 cm long. The speed of bob, when the length makes an angle of 60$$^\circ$$ to the vertical will be (g = 10 m/s2) ____________ m/s.

Accepted Answer

Applying work energy theorem :
w
g
+ w
T
= $$\Delta$$K
$$-$$mgl(1 $$-$$ cos60$$^\circ$$) = $${1 \over 2}$$mv
2
$$-$$ $${1 \over 2}$$mu
2
v
2
= u
2
$$-$$ 2gl(1 $$-$$ cos60$$^\circ$$)
v
2
= 9 $$-$$ 2 $$	imes$$ 10 $$	imes$$ 0.5$$\left( {{1 \over 2}} ight)$$
v
2
= 4
v = 2 m/s

Oscillations

A pendulum bob has a speed of 3 m/s at its lowest position. The pendulum is 50 cm long. The speed of bob, when the length makes an angle of 60$^\circ$ to the vertical will be (g = 10 m/s2) ____________ m/s.

Choose the correct answer: