Physics 1060 - Spring 2020 - Midterm Exam 1 - Posted Version
Problem 1:
You are pulling a toy wagon up a ramp that rises vertically 1 meter for every 8 meters you travel uphill along its surface (see figure). If you let go of the wagon, how will it move? [neglect friction and effects due to the air]
(A) It will accelerate downhill at 1/8th the acceleration due to gravity.
(B) It will accelerate downhill at 1/4th the acceleration due to gravity.
(C) It will move downhill at a constant velocity.
(D) It will accelerate downhill at 8 times the acceleration due to gravity.
Problem 2:
You are graduating and you toss your cap into the air. While the cap is not touching anything and neglecting any effects due to the air, what aspect of the cap's motion remains constant?
(A) Its momentum
(B) Its force
(C) Its angular momentum
(D) Its torque
Problem 3:
The electric field near a positive charge points
(A) away from the charge and does not depend on the distance from the charge.
(B) away from the charge and becomes weaker with increasing distance from the charge.
(C) 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.
Problem 4:
Two coins slide horizontally off a tabletop side-by-side at the same instant and begin to fall. The US quarter was moving twice as fast as the US dime when the two coins left the tabletop. Where and when do the coins hit the level floor beneath the table? [neglect any effects due to the air.]
(A) The quarter hits the ground before the dime, but the two coins land about the same distance from the table.
(B) The two coins hit the ground at the same time, but the quarter lands about twice as far from the table as does the dime.
(C) The dime hits the ground before the quarter, but the quarter lands about twice as far from the table as does the dime.
(D) The two coins hit the ground at the same time and land about the same distance from the table.
Problem 5:
You're at the lake and watch two children jump off a dock. They jump at the same time and at the same speed, but the girl jumps mostly upward while the boy jumps mostly forward. After they leave the dock,
(A) the two children reach the water at the same moment and but the boy travels farther from the dock than does the girl.
(B) the two children reach the water at the same moment and at the same distance from the dock.
(C) the boy reaches the water before the girl.
(D) the girl reaches the water before the boy.
Problem 6:
A hammer's weight acts in the downward direction, yet you can use the steel hammer to pound a nail into the ceiling. Why?
(A) Your downward weight is so much greater than that of the nail that you dominate the hammer's motion.
(B) The nail's downward weight is so much smaller than that of the hammer that the overall force due to gravity on the nail is upward and the nail moves upward into the ceiling.
(C) The upward-moving hammer transfers its upward momentum to the nail by way of a huge upward force exerted on the nail for a short period of time.
(D) Your downward weight is so much greater than that of the hammer that the net force on the hammer is upward as it strikes the nail.
Problem 7:
A positively charged storm cloud is passing overhead as you step into your car in the middle of an open field. For the brief moment, while you are touch both the ground and the car, electric charge can move between the ground and car. When you are completely inside the car and the car's tires insulate it from the ground, what is the car's electric charge?
(A) The car is negatively charged.
(B) The car is positively charged.
(C) The car's charge cannot be determined without measuring it.
(D) The car is electrically neutral.
Problem 8:
You walk on a carpet and accumulate a large static charge. If you reach out to a doorknob with your finger, you'll receive a strong shock. Instead, you reach out to the doorknob with a sharp metal needle in your hand, pointing that needle toward the doorknob. As the needle moves toward the doorknob, you receive
(A) a moderately strong shock (slightly less than without the pin).
(B) no shock at all.
(C) a strong shock anyway (the same as without the pin).
(D) an extra-strong shock (significantly more than without the pin).
Problem 9:
There are two metal balls on your desk, one on the left and one on the right (see figure). Someone has attached a battery to those balls, so the voltage of the left ball is +10 volts and the voltage of the right ball is –10 volts. Midway between the two balls, the electric field points
(A) upward.
(B) downward.
(C) toward the right.
(D) toward the left.
Problem 10:
You hold a positively charged stick near a glass ball and then near a metal ball. What force does the charged stick experience in these two cases?
(A) The charged stick is attracted to the metal ball but not the glass ball.
(B) The charged stick is attracted to both the glass ball and the metal ball.
(C) The charged stick is attracted to the glass ball but not to the metal ball.
(D) The charged stick is attracted to the glass ball but it is repelled by the metal ball.
Problem 11:
A speedboat is pulling a water skier across the water and that skier is traveling in a straight path at a steady speed. The net force experienced by the water skier
(A) points in the backward horizontal direction.
(B) points in the upward vertical direction.
(C) is zero.
(D) points in the forward horizontal direction.
Problem 12:
You are a firefighter and the alarm sounds in your fire station. As you slide down the fire pole at constant velocity, your gravitational potential energy is decreasing. What is becoming of that energy?
(A) It is becoming thermal energy.
(B) It is becoming kinetic energy.
(C) It is becoming downward momentum.
(D) It is becoming downward force.
Problem 13:
While riding on a bus, you place your backpack on the seat next to you. The bus is heading forward at a moderate speed when a child suddenly runs across the street in front of it. The driver slams on the brakes, stopping the bus in time to avoid the child, but your backpack moves forward off the seat and falls to the floor. Why didn't your backpack stay on the seat?
(A) The bus seat pushed the backpack forward, in the direction of the bus's velocity.
(B) The backpack's inertia kept it moving forward as the bus accelerated backward and slowed to a stop.
(C) The backpack pushed itself forward as the bus pushed itself backward.
(D) The bus seat pushed the backpack forward, in the direction opposite the bus's acceleration.
Problem 14:
A particular 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) has a strong electric field near it and that strong field pushes positive charge from the wire onto air molecules.
(B) has a strong electric field near it and that strong field pushes negative charge from the wire onto air molecules.
(C) heats up quickly and boils off electric charge onto the surface of the photoconductor.
(D) 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.
Problem 15:
During a storm, a high-voltage electric power line falls on the car you are driving and it transfers a dangerous amount of positive charge to your car. The car's rubber tires prevent that charge from flowing into the ground. When everything reaches equilibrium, where is the car's charge located?
(A) It is on the inside surface of the car.
(B) It is on the outside surface of the car.
(C) It is on both the outside and inside surfaces of the car.
(D) It is distributed uniformly throughout the car's metal components.
Problem 16:
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 barely moves downward as you push downward on it, so you do almost zero work on it.
(B) its water content gives it more mass and that prevents it from absorbing energy.
(C) it pushes up on your foot just as hard as your foot pushes on it, unlike the soft dry sand.
(D) it stops the downward motion of your foot faster and thus absorbs less of your momentum.
Problem 17:
A seesaw is balanced, with its center of gravity located exactly at its pivot. The seesaw is
(A) oscillating back and forth about equilibrium.
(B) moving with constant angular momentum, which may be zero.
(C) motionless, but it may be horizontal or tilted at any angle.
(D) motionless and horizontal.
Problem 18:
You throw your water bottle straight up and it rises for 2 seconds before reaching its peak height of about 20 meters (66 feet). After only 1 second of rising, what was the water bottle's approximate height?
(A) About 10 meters
(B) About 7.5 meters
(C) About 15 meters
(D) About 5 meters
Problem 19:
You are pulling a wagon full of children up a hill at constant velocity. Which one of the following statements is true?
(A) The net force on the wagon is uphill and you are doing work on the wagon.
(B) The net force on the wagon is zero and you are doing work on the wagon.
(C) The net force on the wagon is uphill and you are doing zero work on the wagon.
(D) The net force on the wagon is zero and you are doing zero work on the wagon.
Problem 20:
A piece of tape is stuck to a glass window. Together, they are electrically neutral. You carefully peel the tape off the window and discover that the tape has a negative electric charge. What is the charge of the window? [Assume that you did not exchange any charge with the tape or window.]
(A) The window is electrically neutral.
(B) Peeling the tape from the window leaves the window with a random charge, which can be positive, negative, or neutral.
(C) The window has a negative electric charge.
(D) The window has a positive electric charge.
Problem 21:
A player kicks the soccer ball almost the entire length of the field. While the ball is traveling in an arc and touching nothing, what horizontal force does the ball experience? [neglect any effects due to the air.]
(A) The ball experiences a horizontal force that pushes it forward. The force is constant.
(B) The ball experiences a horizontal force that is pushes it forward. The force decreases steadily to zero just as the ball hits the ground.
(C) The ball experiences no horizontal force.
(D) The ball experiences a horizontal force that pushes it forward. The force is constant until the ball reaches peak height, then decreases steadily to zero just as the ball hits the ground.
Problem 22:
Someone has filled two basketballs with water. In one ball, the water is pure so the water's rotation is almost independent of the ball's rotation. In the other ball, the water is gelled (someone added gelatin to it) so that it must rotate with the ball. The two balls look identical and have equal weights, so how can you tell which ball contains gelled water?
(A) Twist the two balls back and forth rotationally about their centers. The one that exhibits the most resistance to angular acceleration contains the gelled water.
(B) Drop the two balls from the same height at the same time. The ball that hits the ground first contains the gelled water.
(C) Drop the two balls from the same height at the same time. The ball that hits the ground first contains the pure water.
(D) Shake the two balls back and forth. The one that exhibits the most resistance to acceleration contains the gelled water.
Problem 23:
You are bicycling up a hill at constant velocity. Neglecting any effects due to the air, in which direction is the hill's overall force on the bicycle (i.e., the total force that the hill exerts on the bicycle)?
(A) Upward
(B) Forward horizontally
(C) Uphill
(D) Downhill
Problem 24:
You stand ready to run a long race on a level track. As the race starts, you accelerate forward. What is causing you to accelerate forward?
(A) The support force that the track exerts on you.
(B) The frictional force that the track exerts on you.
(C) You are pushing yourself forward.
(D) Your mass.
Problem 25:
You and a wrapped gift are both electrically neutral. You remove the plastic wrapper from the gift and find that the wrapper is now clinging to your hand. Why?
(A) The wrapper and gift acquired equal but opposite charges when you separated them. The charged wrapper has polarized your hand and is attracted to that polarization.
(B) The wrapper and gift acquired equal but opposite charges when you separated them. The wrapper has given half of its charge to your hand, so the wrapper and your hand now attract one another.
(C) As you moved the wrapper farther from the gift, the wrapper's charge increased and some of that charge began to jump onto your hand. Your charged hand now attracts the charged wrapper.
(D) Both the wrapper and your hand are electrically neutral, so they don't repel. The opposite of repulsion is attraction, so the wrapper and your hand must attract one another.
Problem 26:
You are standing in the middle of motionless bus, with a skateboard under your feet. The light turns green and the bus begins to move forward. Why do you find yourself rolling toward the back of the bus?
(A) The skateboard prevents the bus from pushing you forward, so you remain inertial and the bus leaves you behind.
(B) The bus pushes the bottoms of the skateboard wheels forward, so the tops of the wheels push you backward.
(C) The bus transfers backward momentum to you with the help of the skateboard.
(D) The bus exerts torques on the skateboard wheels and the wheels exert torques on you.
Problem 27:
You are walking a dog on a leash when the dog begins chasing a rabbit. As you and the dog move rapidly forward in a straight line at a steady speed, compare the horizontal forces you and the dog exert on the leash that connects you. [Neglect the leash's mass and weight]
(A) The forward force the dog exerts on the leash is equal in amount to the backward force you exert on the leash.
(B) Because the leash is not accelerating, each of you exerts zero force on the leash.
(C) The forward force the dog exerts on the leash is greater than the backward force you exert on the leash.
(D) The backward force you exert on the leash is greater than the forward force the dog exerts on the leash.
Problem 28:
You are so excited that you high-five a massive bronze statue. Your hand was moving at 1 meter-per-second before hitting the statue's hand, but comes to a complete stop after the impact. If the statue had been wearing a soft wool mitten and your hand had come to a complete stop on that mitten, how would that have affected the momentum your hand transferred to the statue (and mitten) during this impact?
(A) Your hand would have transferred less momentum.
(B) Your hand would have transferred the same momentum, but with a smaller force over a larger distance.
(C) Your hand would have transferred more momentum.
(D) Your hand would have transferred the same momentum, but with a smaller force over a longer time.
Problem 29:
As shown in the figure below, a sharp metal pin has a voltage of –2000 volts and it points toward a wide metal surface with a voltage of +2000 volts. Where in this system can you find a position where the voltage is 0 volts?
(A) At the midway point.
(B) To the right of the midway point.
(C) To the left of the midway point.
(D) There is no position in this system at which the voltage is 0 volts.
Problem 30:
Which of these vehicles is accelerating?
(A) An elevator that is motionless and experiencing a net force of zero.
(B) A train that is moving at a steady speed around a curved track.
(C) An elevator moving downward and experiencing a net force of zero.
(D) A wagon moving up a smooth, straight ramp at a steady speed.
