Physics
Work and Energy
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#169 A body is dropped from height h. On reaching the height (h - x) its velocity will be
A) \(\sqrt{2g(h-x)}\)
B) \(\sqrt{2mg(h-x)}\)
C) \(\sqrt{2gx}\)
D) \(\sqrt{2mgx}\)
#170 Which one of the following is not the unit of work?
A) Electron volt
B) Joule
C) Megawatt day
D) Horse power
#171 A 4 kg body is thrown vertically upward from the ground with a velocity of 5 m/s. Its kinetic energy just before hitting the ground is
A) 25 J
B) 50 J
C) 75 J
D) 100 J
#172 The average power and instantaneous power become equal if work is done at
A) Any rate
B) Variable rate
C) Uniform rate
D) High rate
#173 Proton, electron, neutron, and \(\alpha\)-particles have same momentum. Which of them have highest K.E?
A) Proton
B) Electron
C) Neutron
D) \(\alpha\)-particle
#174 Work done on the body equals to the
A) Change in its K.E always
B) Change in its P.E always
C) Change in its K.E or change in its P.E
D) Neither change in K.E nor change in its P.E
#175 Work done by a force of friction is
A) Always positive
B) Always negative
C) Positive only for small frictional force
D) Positive only for large frictional force
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