The cutting cord on a gas-powered weed cutter is 0.20 m in length. If the motor rotates at the rate of 20 rev/s, what is the tangential speed of the end of the cord?
a. 628 m/s
c. 19 m/s
b. 25 m/s
d. 63 m/s
[Ques. 2] A point on the rim of a 0.30-m radius rotating wheel has a tangential speed of 4.0 m/s. What is the tangential speed of a point 0.10 m from the center of the same wheel?
a. 1.0 m/s
c. 2.7 m/s
b. 1.3 m/s
d. 8.0 m/s
[Ques. 3] For a point on a spinning disc in uniform circular motion, which of the following is not constant?
a. its speed
c. its centripetal acceleration
b. its period of motion
d. the magnitude of its acceleration
[Ques. 4] A 6.0-kg object is falling downward with an acceleration of 3.27 m/s2 . Of the following values, which is nearest to the drag force on the object?
a. 3.3N
c. 20 N
b. 65 N
d. 39 N
[Ques. 5] A solid steel ball is dropped from a great height and when its speed reaches 20 m/s its acceleration downward is 7.35 m/s2 . What would be the terminal velocity in this situation?
a. 80 m/s
c. 40 m/s
b. 60 m/s
d. 20 m/s
[Ques. 6] A sphere is dropped from a great height and when its speed reaches 20 m/s, its acceleration downward is 8.4 m/s2 . If the drag force is proportional to the square of the speed, what will be its acceleration downward when its speed reached 40 m/s?
a. 2.6 m/s2
b. 4.2 m/s2
c. 8.0 m/s2
d. 0 m/s2 because it has now reached terminal velocity.
[Ques. 7] What is an inertial reference frame? It is one
a. that does not accelerate.
c. that accelerates at a constant rate.
b. that accelerates at a varying rate.
d. in which velocities are all constant.
[Ques. 8] A mass is suspended from a string in an airplane. As the plane is in the process of taking off, it is found that the string, instead of being vertical, hangs at an angle of 13 from the vertical. What is the acceleration of the plane at this time?
a. 2.3 m/s2
c. 9.1 m/s2
b. 3.8 m/s2
d. 3.5 m/s2
[Ques. 9] A block is launched up an inclined plane. After going up the plane, it slides back down to its starting position. The coefficient of friction between the block and the plane is 0.3 . The speed of the block when it reaches the starting position on the trip down:
a. is the same as the launching speed. b. is less than the launching speed. c. is more than the launching speed. d. cannot be compared to the launch speed with the information given.
[Ques. 10] A block is launched up an inclined plane. After going up the plane, it slides back down to its starting position. The coefficient of friction between the block and the plane is 0.3 . The time for the trip up the plane:
a. is the same as the time for the trip down.
b. is more than the time for the trip down.
c. is less than the time for the trip down.
d. cannot be found compared without knowing the angle of inclination.
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