A car wash nozzle directs a steady stream of water at 1.5 kg/s, with a speed of 20 m/s, against a car window. What force does the water exert on the glass? Assume the water does not splash back.
a. 30 N
c. 300 N
b. 45 N
d. 440 N
[Ques. 2] Electrons in a particle beam each have a kinetic energy of 3.2 10-17 J. What is the magnitude of the electric field that will stop these electrons in a distance of 0.05 m? (e = 1.6 10-19 C)
a. 2000 N/C
c. 200 N/C
b. 4000 N/C
d. 1000 N/C
[Ques. 3] If a glass of water is on a table with a piece of paper under it, it is relatively easy to pull the paper out without disturbing the glass very much if the pull is done very quickly. This is because with a quick pull:
a. the force on the glass will be less.
b. the momentum of the paper will be greater.
c. the time for the pull will be less.
d. the coefficient of kinetic friction will be less.
[Ques. 4] A proton moving at 6.0 104 m/s is projected at an angle of 30 above a horizontal plane. If an electric field of 400 N/C is acting down, how long does it take the proton to return to the horizontal plane? (Hint: Ignore gravity. mproton = 1.67 10-27 kg, qproton = 1.6 10-19 C)
a. 7.8 10-6 s
c. 7.8 10-7 s
b. 1.6 10-6 s
d. 3.9 10-6 s
[Ques. 5] Lonnie pitches a baseball of mass 0.15 kg. The ball arrives at home plate with a speed of 40 m/s and is batted straight back to Lonnie with a return speed of 60 m/s. If the bat is in contact with the ball for 0.050 s, what is the impulse experienced by the ball?
a. 360 Ns
c. 400 Ns
b. 20 Ns
d. 15 Ns
[Ques. 6] In x-ray machines, electrons are subjected to electric fields as great as 4.0 105 N/C. Find an electron's acceleration in this field. (me = 9.11 10-31 kg, e = 1.6 10-19 C)
a. 1.1 1017 m/s2
c. 3.6 108 m/s2
b. 7.0 1016 m/s2
d. 4.6 1010 m/s2
[Ques. 7] A crane drops a 0.40-kg steel ball onto a steel plate. The ball's speeds just before impact and after are 4.5 m/s and 4.2 m/s, respectively. If the ball is in contact with the plate for 0.030 s, what is the magnitude of the average force that the ball exerts on the plate during impact?
a. 87 N
c. 3.0 N
b. 116 N
d. 3.5 N
[Ques. 8] An electron with a speed of 2.0 106 m/s moves into a uniform electric field of 325 N/C that is parallel to the electron's motion. How long does it take to bring the electron to rest? (me = 9.11 10-31 kg, e = 1.6 10-19 C)
a. 3.5 10-8 s
c. 2.3 10-8 s
b. 2.3 10-6 s
d. 1.2 10-7 s
[Ques. 9] Alex throws a 0.15-kg rubber ball down onto the floor. The ball's speed just before impact is 6.5 m/s and just after is 3.5 m/s. If the ball is in contact with the floor for 0.050 s, what is the magnitude of the average force applied by the floor on the ball?
a. 60 N
c. 30 N
b. 133 N
d. 3.5 N
[Ques. 10] A proton initially moves left to right long the x axis at a speed of 2.00 103 m/s. It moves into an electric field, which points in the negative x direction, and travels a distance of 0.300 m before coming to rest. If the proton's mass and charge are 1.67 10-27 kg and 1.60 10-19 C, respectively, what is the magnitude of the electric field?
a. 13.9 N/C
c. 28.3 N/C
b. 0.0696 N/C
d. 0.104 N/C
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