A V m 2. A force F at an angle 6 above the horizontal is used to pull a heavy su

Question

A V m 2. A force F at an angle 6 above the horizontal is used to pull a heavy suitcase of weight mga distance d along a level floor at constant velocity. The coefficient of friction between the floor and the suitcase is The work W. done by the frictional force is: (A) -Fd cos 0 (B) mgh Fd cos e (C) -u Fd cos (D) mgd If the nit for force is F, the unit for velocity gd cos e (A) F v. and the unit for time T, then the it for energy is: (D) FIT: (E) FV2rT2 A. (A) orce of 10 N stretches a spring that has a spring constant of 20 N/m. The potential energy stored in the spring is 2.5 J (B) 5.0 J J (D) 40 J (E) 200 J (C) 10 5. A 2 kg ball is attached to a 0.80 m string and in a horizontal circle at aconstant speed of 6 m/s. The work done on the ball during each revolution is: (A) 450 J (B) 90 J (C) 72 J (D) 16 J (E) zero 6. A pendulum bob of mass m on a cord of length Lis pulled sideways until the cord makes an angle with the vertical as shown in the figure to the right. The change in potential energy of the bob during the displacement is: mgL (1-cos e) (B) mgL (1-sin 0) (C) mg L sin e (D) mgL cos 0 (E) 2mgL (1-sin e) in 7. A force F directed at an angle 0 above the horizontal is used to pull a crate a distance D across a level floor. The work done by the force F is (A) FD (B) FD cos 0 (C) FD sin 0 (D) mg sin 0 (E) mg D cos 8. A compressed spring has 16 Jof potential energy. What is the maximum speed it can impart to a 2 kg object? (D) 8.0 m/s (E) 16 m/s (C) 5.6 m/s (A) 2.8 m/s (B) 400 m/s 9. A softball player catches a ball of mass m, which is moving towards her with horizontal speed V. While bringing the ball to rest, her hand moved a distance d. Assuming constant deceleration, the horizontal back feree exerted on the ball by the hand is

Explanation / Answer

According to the given problem,

Answer : [D] zero

Reason: The only force is perpendicular to the displacement therefore it does not do work.

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