A girl and her bicycle have a total mass of 46.0 kg. At the top of the hill her speed is 6.0 m/s, and her speed doubles as she rides down the hill. The hill is 15.0 m high and 105 m long. How much kinetic energy and potential energy is lost to friction?
a. 4.3E+3 J
b. 7.6E+3 J
c. 3.5E+3 J
d. 4.4E+3 J
e. 4.2E+3 J
[Ques. 2] A 26.0-N crate starting at rest slides down a rough 4.8-m-long ramp, inclined at 21.0 with the horizontal. 18 J of energy is lost to friction. What will be the speed of the crate at the bottom of the incline?
a. 27.1 m/s
b. 5.81 m/s
c. 6.36 m/s
d. 4.49 m/s
[Ques. 3] When an object is dropped from a tower, what is the effect of the air resistance as it falls?
a. does positive work
b. increases the object's kinetic energy
c. increases the object's potential energy
d. None of the above choices are valid.
[Ques. 4] A simple pendulum, 2.0 m in length, is released by a push when the support string is at an angle of 25 from the vertical. If the initial speed of the suspended mass is 1.6 m/s when at the release point, to what maximum angle will it move in the second half of its swing?
a. 86.3
b. 32.8
c. 39.1
d. 83
e. 180
[Ques. 5] A simple pendulum, 2.6 m in length, is released with a push when the support string is at an angle of 45.0 from the vertical. If the initial speed of the suspended mass is 1.25 m/s when at the release point, what is its speed at the bottom of the swing? (g = 9.8 m/s2)
a. 4.1 m/s
b. 3.9 m/s
c. 4.1 m/s
d. 16 m/s
e. 7.2 m/s
[Ques. 6] A pendulum consists of a mass m suspended from a string of length L. When the pendulum is swinging, how much greater is the mass's potential energy when the string is displaced from the vertical by the angle than when the mass is at the lowest position?
a. mgLsin
b. mgLcos
c. mgL(1 sin) d. mgL(1 cos)
[Ques. 7] A bobsled makes a run down an ice track starting at 250 m vertical distance up the hill. If there is no friction, what is the velocity at the bottom of the hill?
a. 35.0 m/s
b. 49.5 m/s
c. 46.7 m/s
d. 70.0 m/s
e. 58.3 m/s
[Ques. 8] A baseball outfielder throws a baseball of mass 0.36 kg at a speed of 34.0 m/s and initial angle of 30. What is the kinetic energy of the baseball at the highest point of the trajectory? Ignore air friction.
a. zero
b. 312 J
c. 156 J
d. 52.0 J
e. 208 J
[Ques. 9] A pole vaulter clears 3.98 m. With what speed does he strike the mat in the landing area?
a. 78.0 m/s
b. 6.25 m/s
c. 8.83 m/s
d. 4.42 m/s
e. 0.226 m/s
[Ques. 10] An airliner with mass 90 000 kg is flying at 900 km/h at a height of 15.0 km. What is its total energy (kinetic + potential) if the total was 0 when the airliner was at rest on the ground?
a. 5.0E+10 J
b. 3.6E+10 J
c. 1.3E+10 J
d. zero
e. 1.6E+10 J
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