PHYS 1060 Midterm Exam 1, Spring 2011 - Solutions
Problem 1:
When a flashlight experiences a short circuit, the current in the flashlight bypasses
Answer: (A) the lightbulb. [96.4% picked]
Why: Video Discussion
Problem 2:
You are dragging a large couch across the floor in a straight line at a steady speed. Which of the following statements about the forces acting on the couch is correct?
Answer: (B) The amount of force that you're exerting on the couch must be equal to the amount of force that friction is exerting on it. [87.5% picked]
Why: Video Discussion
Problem 3:
The positive terminal and negative terminal of a 9 volt battery are about 1/4 inch (6 millimeters) apart. In keeping with its name, the battery's positive terminal has a voltage that is 9 volts greater than the voltage of its negative terminal. Midway between those two terminals, the electric field
Answer: (A) points away from the positive terminal and toward the negative terminal. [45.2% picked]
Why: Video Discussion
Problem 4:
A glass bottle and its adhesive label are both electrically neutral. You hold the bottle and label with insulating rubber gloves and peel the label off the bottle. The label acquires a positive net charge. As you pull the label away from the bottle with your gloves, the voltage of label
Answer: (B) increases, but its net charge remains constant. [89.1% picked]
Why: Video Discussion
Problem 5:
Which type(s) of friction convert work into thermal energy?
Answer: (A) Sliding friction but not static friction. [83.9% picked]
Why: Video Discussion
Problem 6:
You have two ordinary alkaline batteries. One is a small AAA battery and the other is a large D battery. Compared to the AAA battery, the D battery provides
Answer: (A) the same voltage difference between its terminals but it can pump more charge before it runs out of energy. [90.3% picked]
Why: Video Discussion
Problem 7:
A rigid two-blade wind turbine that is experiencing zero net torque
Answer: (D) has a constant angular velocity. [93.1% picked]
Why: Video Discussion
Problem 8:
You throw your running shoes into the closest, but they bounce off the concrete wall and return to the middle of your rug. During their bounce, the shoes
Answer: (B) retained essentially all of their energy but transferred large amounts of momentum to the wall. [88.7% picked]
Why: Video Discussion
Problem 9:
You are cleaning up litter on the beach and have just thrown an empty bottle toward the recycling bin. Neglecting any effects due to the air, the net force on the bottle when it is midway between you and the recycling bin
Answer: (C) points straight down. [89.1% picked]
Why: Video Discussion
Problem 10:
The voltage difference between the two ends of a metal wire is proportional to
Answer: (A) the current passing through that wire. [65.3% picked]
Why: Video Discussion
Problem 11:
A helicopter is hovering motionless above a disabled boat, while rescue workers use a rope to lift an injured sailor. While that sailor is being lifted upward, the net force on the motionless helicopter is
Answer: (C) zero. [77.8% picked]
Why: Video Discussion
Problem 12:
You are moving two wagons on level ground. One wagon has a mass of 100 kilograms and the other has a mass of 200 kilograms. Neglect friction and air resistance. When you push equally hard on each wagon, the 100 kilogram wagon
Answer: (D) accelerates twice as quickly as the 200 kilogram wagon. [81.9% picked]
Why: Video Discussion
Problem 13:
Your car skids off the road in bad weather and crashes into a tree. Fortunately, the airbag inflates and protects your head from injury. By coming to a stop in the airbag instead of on the steering wheel, your head transfers
Answer: (D) the same amount of momentum to the car but over a longer period of time and with a smaller force. [97.6% picked]
Why: Video Discussion
Problem 14:
A Frisbee-catching dog leaps high into the air to capture a passing Frisbee. During the time that the dog is not touching the ground and neglecting any effects due to the air, the one aspect of the dog's motion that is constant is the dog's
Answer: (B) angular momentum. [75.4% picked]
Why: Video Discussion
Problem 15:
You are watching a tennis match and the server has just hit the ball toward her opponent on the other side of the court. Neglect any effects due to the air. Once the tennis ball has left the server's tennis racket and is traveling forward, the ball experiences
Answer: (D) no horizontal force in the forward direction. [91.9% picked]
Why: Video Discussion
Problem 16:
Two balloon are a few inches apart and hanging from insulating strings. Each balloon is electrically neutral. You rub your wool sweater against one of the balloons and that balloon becomes negatively charged. The negatively charged balloon
Answer: (C) electrically polarizes the other balloon and the two balloons attract one another. [96.0% picked]
Why: Video Discussion
Problem 17:
A xerographic copier uses a very thin wire with a large positive voltage to spray electric charges onto the surface of its photoconductor. The thin wire
Answer: (C) has a strong electric field near it and that strong field pushes charge from the wire onto air molecules. [89.5% picked]
Why: Video Discussion
Problem 18:
You walk on a carpet and accumulate a large static charge. You touch a solid gold jewelry box on your wooden bureau and transfer some of your charge to the box. When you remove your hand, the box's charge is
Answer: (C) on its outer surface. [96.8% picked]
Why: Video Discussion
Problem 19:
Running on soft dry sand is exhausting, so you switch to running on hard wet sand. The hard wet sand removes less energy from you because
Answer: (D) it barely moves downward as you push downward on it, so you do almost zero work on it. [78.2% picked]
Why: Video Discussion
Problem 20:
Two identical children run along a horizontal platform side by side and jump into a swimming pool at the same moment. They both jump equally hard, but one child jumps upward while the other child jumps forward. You watch them fall and see that
Answer: (B) the child who jumped forward reaches the water before the child who jumped upward. [86.3% picked]
Why: Video Discussion
Problem 21:
You just dried your laundry and one of your socks is partly inside-out. You hold one end of the sock and jerk that end suddenly away from the rest of the sock. The sock immediately opens up to full length. What caused the sock to open up to full length?
Answer: (C) The sock's inertia. [84.7% picked]
Why: Video Discussion
Problem 22:
The battery in your cell phone has two wires connecting it to the phone. If one of those two wires breaks, the cell phone will
Answer: (C) not work at all. [95.6% picked]
Why: Video Discussion
Problem 23:
A battery charger recharges a battery by
Answer: (C) sending current through the battery from its positive terminal to its negative terminal. [86.3% picked]
Why: Video Discussion
Problem 24:
You are walking a dog on a leash when you come upon a squirrel. The dog suddenly picks up speed and is now pulling you forward with a force of 100 newtons. Neglecting the mass of the leash itself, the backward force you are now exerting on the dog is
Answer: (A) 100 newtons. [85.5% picked]
Why: Video Discussion
Problem 25:
A walk across a synthetic carpet has left you covered with static electric charge and you are about to reach out to a metal pipe. If you move your hand slowly toward the pipe, a spark will occur when your hand is about 1 inch from the pipe. If you hold a sharp metal needle in your hand, aimed at the pipe, and move your hand slowly toward the pipe,
Answer: (C) no spark will occur. [98.8% picked]
Why: Video Discussion
Problem 26:
You are standing on a cliff at the edge of a lake and dropping pebbles into the water. Each pebble takes 2 seconds to reach the water. After it has fallen for only 1 second, one of these pebbles is located
Answer: (C) much closer to you than to the water. [74.2% picked]
Why: Video Discussion
Problem 27:
When you turn the key to start your car, the car's battery provides electric power to the car's starter motor. Current flows through the starter motor from
Answer: (D) higher voltage to lower voltage. Current flows through the battery from lower voltage to higher voltage. [89.5% picked]
Why: Video Discussion
Problem 28:
You have two bowling balls, one of which weighs twice as much as the other. The balls roll off a horizontal table at the same time, but the lighter ball leaves the table at twice the velocity of the heavier ball. In this situation, both balls hit the floor
Answer: (A) at approximately the same time, but the lighter ball hits considerably farther from the table than the heavier ball. [68.1% picked]
Why: Video Discussion
Problem 29:
You are involved in a game of tug-o-war with a plastic clothesline. The two teams are pulling at opposite ends of the cord and each team is trying to drag the other team across a line marked on the ground. After a few minutes without progress, your team suddenly pulls the rope toward you especially hard. The opposing team has anticipated this action and is able to keep their end of the rope from moving. Your end of the rope stretches toward you and the rope breaks. Breaking the rope required energy and that energy was provided by
Answer: (C) your team. [87.5% picked]
Why: Video Discussion
Problem 30:
The electric field near a positive charge points
Answer: (A) away from the charge and becomes weaker with increasing distance from the charge. [69.8% picked]
Why: Video Discussion