QJEEM21Ph19af: JEE Main 2021 Physics - Class 11 JEEM21Ph19af Solution: A pendulum bob has a speed of 3 m/s at its lowest position. The …

Question

Verified Solution • 2025–26 Session moderate

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 =

Δ

K

-

mgl(1

-

cos60

^{\circ}

) =

\frac{1}{2}

mv²

-

\frac{1}{2}

mu²

v² = u²

-

2gl(1

-

cos60

^{\circ}

)

v² = 9

-

2

\times

10

\times

0.5

(\frac{1}{2})

v² = 4

v = 2 m/s

Step-by-Step Verified Solution