7 - Work and Kinetic Energy

# 7 - Work and Kinetic Energy - Q1 Which of the following...

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Q1) Which of the following statements is true? 1) Joe will probably get hit and need plastic surgery. 2) Joe is safe because there is air resistance. 3) Joe would be safe even if we ignored air resistance. Q2) No work is done by gravity on a bowling ball that rolls along a bowling alley because 1) no force acts on the ball 2) no distance is covered by the ball 3) the force on the ball is perpendicular to the ball’s motion 4) all of the above 5) none of the above Q3) Which requires more work: lifting a 50 kg sack vertically 2 meters or lifting a 25 kg sack vertically 4 meters? 1) lifting the 50 kg sack 2) lifting the 25 kg sack 3) both require the same amount of work

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Q4) The figure shows four situations in which a force acts on a box while the box slides rightward a distance d across a frictionless floor. The magnitudes of the forces are identical; their orientations are as shown. Rank the situations according to the work done on the box during the displacement, from most positive to most negative. 1) d, c, b, a 2) a, b, c, d 3) a, c, d, b 4) c, d, b, a 5) none of the above Q5) Can the normal force ever do nonzero work on an object? 1) yes 2) no Q6) A rock of mass m is twirled on a string in a horizontal plane. The work done by the tension in the string on the rock is
1) + 2) - 3) 0

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When a person walks, the force of friction between the floor and the person's feet accelerates the person forward. The floor does
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7 - Work and Kinetic Energy - Q1 Which of the following...

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