Four point charges are on the rim of a circle. The charges are (in mC) +0.50, +3.0, -1.0, -0.50 . If the electrical potential at the circle's center due to the +0.5 charge alone is 4.5 104 V, what is the total potential at the center due to the four charges combined?
a. 18 104 V
c. zero
b. 4.5 104 V
d. -4.5 104 V
[Ques. 2] A helicopter stays aloft by pushing large quantities of air downward every second. What mass of air must be pushed downward at 30.0 m/s every second to keep a 1000 kg helicopter aloft?
a. 120 kg
c. 327 kg
b. 245 kg
d. 490 kg
[Ques. 3] A 9.0-V battery moves 200 mC of charge through a circuit running from its positive terminal to its negative terminal. How much energy was delivered to the circuit?
a. 4.5 x 103 J
c. 2.2 mJ
b. 1.8 J
d. 0.18 J
[Ques. 4] A model car is propelled by a cylinder of carbon dioxide gas. The cylinder emits gas at a rate of 4.5 g/s with an exit speed of 80.0 m/s. The car has a mass of 200 g, including the CO2 cylinder. Starting from rest, what is the car's initial acceleration?
a. 0.90 m/s2
c. 9.0 m/s2
b. 1.8 m/s2
d. 36 m/s2
[Ques. 5] An ion is released from rest and moves due to the force from an electric field from a position in the field having a potential of 14 V to a position having a potential of 8 V. The ion:
a. can have either a positive or a negative charge.
b. must be neutral.
c. must have a positive charge.
d. must have a negative charge.
[Ques. 6] Mitch throws a 100-g lump of clay at a 200-g target, which is at rest on a horizontal surface. After impact, the target, including the attached clay, slides 2.1 m before stopping. If the coefficient of friction is = 0.50, find the speed of the clay before impact.
a. 4.5 m/s
c. 27 m/s
b. 14 m/s
d. 36 m/s
[Ques. 7] An electron is released from rest at the negative plate of a parallel-plate capacitor. If the distance across the plates is 5.0 mm and the potential difference across the plates is 20 V, with what velocity does the electron hit the positive plate? (me = 9.1 10-31 kg, e = 1.6 10-19 C)
a. 1.3 106 m/s
c. 2.7 106 m/s
b. 1.0 106 m/s
d. 5.3 106 m/s
[Ques. 8] A double satellite is launched into space. It consists of a satellite of mass m and another satellite of mass 5m. The connecting mechanism of these satellites is an explosive bolt and a compressed spring, both of negligible mass. The bolt is exploded and the satellites drift apart having been pushed by the spring. When the less massive satellite has moved a distance of 2.5 m from the center of mass of the double satellite, how far away from it is the satellite of greater mass?
a. 3.0 m
c. 0.10 m
b. 12 m
d. 0.50 m
[Ques. 9] If the distance between two isolated parallel plates that are oppositely charged is doubled, the electric field between the plates is essentially unchanged. However, the:
a. charge on each plate will double.
b. force on a charged particle halfway between the plates will get twice as small.
c. potential difference between the plates will double.
d. force on a charged particle halfway between the plates will get four times as small.
[Ques. 10] A 4.0 ft by 8.0 ft sheet of plywood of uniform density and thickness lies in the 1st quadrant with its long side along the x axis, one corner at the origin, and the diagonally opposite corner at position (x, y) = (8.0 ft, 4.0 ft). The lower right 2.0 ft by 4.0 ft quarter of the sheet is removed from the sheet. What are the coordinates of the center of mass of the remaining portion of the sheet?
a. (2.0 ft, 4.0 ft)
c. (3.3 ft, 1.7 ft)
b. (1.0 ft, 2.0 ft)
d. (3.3 ft, 2.3 ft)
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