Physics
Work and Energy
Page 11 of 23
#81 A constant force $F=50\,\text{N}$ acts through $s=10\,\text{m}$ at $\theta=30^\circ$. The work done is:
A) $F+s$
B) $50s\,\cos30^\circ$
C) $Fs$
D) $F/s$
#82 Instantaneous power delivered by a constant force is:
A) $P=\vec F\cdot\vec v$
B) $P=Fv\sin\theta$
C) $P=F/v$
D) $P=F^2v$
#83 For a conservative force, the potential energy function $U$ satisfies:
A) $\vec F=+\nabla U$
B) $\nabla\times\vec F=\nabla U$
C) $\vec F=-\nabla U$
D) $\nabla\cdot\vec F=U$
#84 The work–energy theorem for a particle of mass $m$ is:
A) $W_{\text{net}}=\Delta K$
B) $W_{\text{net}}=\Delta p$
C) $W_{\text{net}}=\Delta U$
D) $W_{\text{net}}=m\Delta v$
#85 The work–energy theorem for a particle of mass $m$ is:
A) $W_{\text{net}}=m\Delta v$
B) $W_{\text{net}}=\Delta p$
C) $W_{\text{net}}=\Delta U$
D) $W_{\text{net}}=\Delta K$
#86 A constant force $F=10\,\text{N}$ acts through $s=2\,\text{m}$ at $\theta=30^\circ$. The work done is:
A) $Fs$
B) $F/s$
C) $10s\,\cos30^\circ$
D) $F+s$
#87 Energy stored in a spring stretched by $x$ is:
A) $kx$
B) $kx^2$
C) $k/x$
D) $\tfrac12 kx^2$
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