PHYS2210: In-Class Exercises 02/27/2025.tst
Name___________________________________
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) A 60.0-kg person rides in elevator while standing on a scale. The elevator is traveling
downward but slowing down at a rate of 2.00 m/s2. The reading on the scale is closest
to
A) 708 N.
B) 120 N.
C) 469 N.
D) 349 N.
E) 589 N.
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1)
2) The figure shows a 100-kg block being released from rest from a height of 1.0 m. It then
takes it 0.90 s to reach the floor. What is the mass m of the other block? The pulley has
no appreciable mass or friction.
A) 54 kg
B) 60 kg
C) 42 kg
2
D) 48 kg
2)
3) A system comprising blocks, a light frictionless pulley, a frictionless incline, and
connecting ropes is shown in the figure. The 9.0-kg block accelerates downward when
the system is released from rest. The tension in the rope connecting the 6.0-kg block and
the 4.0-kg block is closest to
A) 42 N.
B) 33 N.
C) 39 N.
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D) 30 N.
E) 36 N.
3)
4) In the figure, a 900-kg crate is on a rough surface inclined at 30°. A constant external
force P = 7200 N is applied horizontally to the crate. While this force pushes the crate a
distance of 3.0 m up the incline, its velocity changes from 1.2 m/s to 2.3 m/s. How
much work does friction do during this process?
A) -7200 J
B) -3700 J
C) +7200 J
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D) +3700 J
E) zero
4)
5) In the figure, two identical ideal massless springs have unstretched lengths of 0.25 m
and spring constants of 700 N/m. The springs are attached to a small cube and stretched
to a length L of 0.30 m as in Figure A. An external force P pulls the cube a distance
D = 0.020 m to the right and holds it there. (See Figure B.) The external force P, that
holds the cube in place in Figure B, is closest to
A) 28 N.
B) 25 N.
C) 14 N.
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D) 21 N.
E) 18 N.
5)
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Answer Key
Testname: PHYS2210_IN_CLASS_EXERCISES_02272025
1) A
2) B
3) A
4) B
5) A
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