Keep the term that carries the energy

A 2 kg pendulum bob hangs from a 1.5 m string. It is raised through θ = 0.080 rad from its lowest position. Use g = 10 m/s² and the leading small-angle approximation.

Find the gain in gravitational potential energy.

Organize the givens & assumptions

Bob mass: 2 kg
String length: 1.5 m
Angle from the lowest position: 0.080 rad
g = 10 m/s²

Point bob, massless inextensible string, small angle in radians. Keep the leading nonzero term in 1 − cos θ.

A $2.4\ \mathrm J$
B $0.096\ \mathrm J$
C $0$
D $0.192\ \mathrm J$

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