Physics
Work and Energy
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#25 Negative work implies:
A) force has component opposite to displacement
B) no force
C) speed increases
D) mass decreases
Answer: A
#26 When is work maximum for given $F$ and $s$?
A) $\theta=0^\circ$
B) $\theta=90^\circ$
C) $\theta=180^\circ$
D) $\theta=45^\circ$
Answer: A
#27 If $W=Fs\cos\theta$ and $\theta=180^\circ$, then $W$ is:
A) negative
B) positive
C) zero
D) undefined
Answer: A
#28 Kinetic energy is doubled if:
A) speed becomes $v\sqrt{2}$
B) speed becomes $2v$
C) mass halves
D) speed becomes $v/2$
Answer: A
#29 Unit of work in CGS is:
A) erg
B) dyne
C) tesla
D) ohm
Answer: A
#30 Potential energy is:
A) relative to a reference level
B) absolute quantity
C) independent of reference
D) always zero
Answer: A
#31 Work done by spring force from $x=0$ to $x$ is:
A) $-\tfrac12 kx^2$
B) $+\tfrac12 kx^2$
C) $kx$
D) $-kx$
Answer: A
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