PHYS 1060 Spring 2011

PHYS 1060 Midterm Exam 1, Spring 2011

Problem 1:

When a flashlight experiences a short circuit, the current in the flashlight bypasses

(A) the lightbulb.

(B) the switch.

(D) the plastic case.

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?

(A) The amount of force that you're exerting on the couch must be more than the amount of its weight.

(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.

(C) The amount of force that you're exerting on the couch must be more than the amount of force that friction is exerting on it.

(D) If you were to exert twice as much force on the couch, it would slide across the floor twice as fast.

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

(A) points away from the positive terminal and toward the negative terminal.

(B) points toward the positive terminal and away from the negative terminal.

(D) is 4.5 volts.

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

(A) increases and its net charge increases.

(B) increases, but its net charge remains constant.

(D) remains constant, but its net charge decreases.

Problem 5:

Which type(s) of friction convert work into thermal energy?

(A) Sliding friction but not static friction.

(B) Neither static friction nor sliding friction.

(D) Both static friction and sliding friction.

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

(A) the same voltage difference between its terminals but it can pump more charge before it runs out of energy.

(B) a larger voltage difference between its terminals but it can pump the same amount of charge before it runs out of energy.

(D) a smaller voltage difference between its terminals but it can pump much more charge before it runs out of energy.

Problem 7:

A rigid two-blade wind turbine that is experiencing zero net torque

(A) is motionless and may be horizontal or tilted.

(B) is motionless and horizontal.

(D) has a constant angular velocity.

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

(A) retained essentially all of their momentum but transferred large amounts of energy to the wall.

(B) retained essentially all of their energy but transferred large amounts of momentum to the wall.

(D) transferred large amounts of momentum and energy to the wall.

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

(A) points down and away from you.

(B) is zero.

(D) points up and away from you.

Problem 10:

The voltage difference between the two ends of a metal wire is proportional to

(A) the current passing through that wire.

(B) one divided by the net charge of that wire.

(D) one divided by the current passing through that wire.

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

(A) upward and equal to the sailor's weight.

(B) downward and equal to the sailor's weight.

(D) downward and equal to the sailor's weight plus the helicopter's weight.

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

(A) accelerates half as quickly as the 200 kilogram wagon.

(B) moves at half the velocity of the 200 kilogram wagon.

(D) accelerates twice as quickly as the 200 kilogram wagon.

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

(A) less momentum to the car and with a smaller force.

(B) the same amount of momentum to the car in the same period of time but with a smaller force.

(D) the same amount of momentum to the car but over a longer period of time and with a smaller force.

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

(A) velocity.

(B) angular momentum.

(D) momentum.

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

(A) a forward horizontal force until it reaches the midpoint of its trip across the tennis court and then a backward horizontal force for the remainder of its trip.

(B) a forward horizontal force that diminishes gradually as the ball approaches the opponent's side of the court.

(D) no horizontal force in the forward direction.

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

(A) exerts no electrostatic force on the other balloon because the other balloon has equal numbers of positive and negative charges.

(B) electrically polarizes the other balloon and the two balloons repel one another.

(D) exerts no electrostatic force on the other balloon because the other balloon is uncharged.

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

(A) heats up quickly and boils off electric charge onto the surface of the photoconductor.

(B) has a weak electric field near it and that weak field easily permits the transfer of charge from the wire to the surface of the photoconductor.

(D) is able to move charge quickly enough to produce finely detailed light and dark spots on the copies.

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

(A) on both its inner and outer surfaces.

(B) on its inner surface.

(D) distributed throughout the metal.

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

(A) it pushes up on your foot just as hard as your foot pushes on it, unlike the soft dry sand.

(B) its water content gives it more mass and that prevents it from absorbing energy.

(D) it barely moves downward as you push downward on it, so you do almost zero work on it.

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

(A) the two children reach the water at the same moment and at the same distance from the pool's edge.

(B) the child who jumped forward reaches the water before the child who jumped upward.

(C) the two children reach the water at the same moment and but the child who jumped forward travels farther from the pool's edge than does the other child.

(D) the child who jumped upward reaches the water before the child who jumped forward.

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?

(A) A support force from the dryer.

(B) A frictional force from the dryer.

(D) The sock's weight.

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

(A) work at approximately full volume, but will only be able to make calls when you have a good signal.

(B) work at approximately half volume, but will still be able to make calls as usual.

(D) work at approximately half volume and will only be able to make calls when you have a good signal.

Problem 23:

A battery charger recharges a battery by

(A) removing positive charges from the battery's positive terminal and negative charges from its negative terminal.

(B) connecting a wire between the battery's positive terminal and its negative terminal.

(D) sending current through the battery from its negative terminal to its positive terminal.

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

(A) 100 newtons.

(B) zero newtons.

(D) more than 100 newtons

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,

(A) a spark will occur when your hand is much more than 1 inch from the pipe.

(B) a spark will occur when your hand is about 1 inch from the pipe.

(D) a spark will occur when your hand is much less than 1 inch from the pipe.

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

(A) much closer to the water than to you.

(B) slightly closer to you than to the water.

(D) about midway between you and the water.

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

(A) lower voltage to higher voltage. Current flows through the battery from higher voltage to lower voltage.

(B) lower voltage to higher voltage. Current flows through the battery from lower voltage to higher voltage.

(D) higher voltage to lower voltage. Current flows through the battery from lower voltage to higher voltage.

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

(A) at approximately the same time, but the lighter ball hits considerably farther from the table than the heavier ball.

(B) at approximately the same time and at the same distance from the table.

(D) at approximately the same distance from the table, but the heavier ball hits the floor well before the lighter ball.

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

(A) neither team. It was instead provided by chemical potential energy in the rope itself.

(B) both teams.

(D) the opposing team.

Problem 30:

The electric field near a positive charge points

(A) away from the charge and becomes weaker with increasing distance from the charge.

(B) toward the charge and does not depend on the distance from the charge.

(D) toward the charge and becomes weaker with increasing distance from the charge.