phys 1600 final exam -DR. Merrill Auburn University
A uniform disk of radius 20 cm, mass 2 kg and angular momentum 0.4 kg m2/s is spinning horizontally about its center with constant angular velocity. How much angular displacement occurs in 2 s? A) 4 rad B) 10 rad C) 20 rad
C) 20 rad
The figure shows a 100 g block of copper (ρ = 8900 kg/m3) and a 100 g block of aluminum (ρ = 2700 kg/m3) connected by a massless string that runs over two massless, frictionless pulleys. The two blocks exactly balance, since they have the same mass. Now suppose that the two masses are completely submerged in water. What will happen? A) the copper block will fall, the aluminum block will rise. B) the aluminum block will fall, the copper block will rise C) Nothing will change D) Both blocks will rise.
A) The copper block will fall, the aluminum block will rise.
You need to make a sharp turn on a flat road, making a radius of curvature of 15 meters. How does the required force of static friction between your tires and the road compare if you make the turn at 30 mph vs. 60 mph? A) The force of friction needs to be four times as large. B) The force of friction needs to be twice as large. C) The force of friction is the same for both speeds since the radius of curvature is the same.
A) The force of friction needs to be four times as large.
The motions of a car and a truck along a straight road are represented by the velocity-time graphs in the figure. The two vehicles are initially alongside each other at time t = 0. At time T, what is true about these two vehicles since time t = 0? A) The truck will have traveled further than the car. B) The car will have traveled further than the truck. C) The truck and the car will have traveled the same distance.
A) The truck will have traveled further than the car.
1. An object of mass 8 kg is attached to an ideal massless spring and allowed to hang in the Earth's gravitational field. The spring stretches 3.6 cm before it reaches its equilibrium position. If this system is allowed to oscillate, what will be its frequency? a. 2.6 Hz b. 0.0045 Hz c. 0.67 Hz d. 2.1 Hz e. 1.3 Hz
A. 2.6
The figure shows a 2000 kg cable car descending a high hill. A counterweight of mass 1800 kg on the other side of the hill provides a force that helps to slow down the car. Without the counterweight the car would accelerate down the slope, so the car also applies its breaks. The result is that the car descends at constant speed. Assume that there is no friction between the slope and the car or counterweight. How much braking force does the cable car need to descend at constant speed? a) 3800 N b) 2900 N c) 2000 N d) 980 N e) 0 N
A. 3800N
A certain wave has a period of 12 hours, an amplitude of 1.5 m, and a speed of 750 km/hr. What is the distance between adjacent crests of these waves? a. 9000 km b. 32,400 km c. 9000 m d. 32,400 m e. 2500 m
A. 9000km
Two balls are thrown upward, ball P at an angle of 64o above the horizontal and ball Q at an angle of 46o above the horizontal. Both are thrown at the same initial speed. Which ball stays in the air longer? Ignore the effects of air resistance. A) Ball P B) Ball Q C) Both stay in the air for the same amount of time
A. Ball P
particle is confined to more only along the x-axis. The position of the particle as a function of time is given by , where 2.0 /, 3.0 /, and 8.0 . What is the instantaneous velocity of the particle at t=2.0 s? A) ‐4.0 m/s B) 12.0 m/s C) 4.0 m/s D) 2.0 m/s E) ‐2.0 m/s
B) 12.0 m/s
You are standing on the floor. A mouse runs on the floor towards your feet. When the mouse is one meter away from your feet, its angular momentum about your belly button is ... A) Zero B) Non-zero and parallel to the floor C) Non-zero and perpendicular to the floor D) in the direction of the velocity of the mouse
B) Non-zero and parallel to the floor
During a collision with a wall, the velocity of a 0.2 kg ball changes from 20 m/s toward the wall to 12 m/s away from the wall. If the time the ball was in contact with the wall was 60 ms, what was the magnitude of the average force applied to the ball? a. 40 N b. 107 N c. 16.7 N d. 26.7 N e
B. 107N
. A block on an inclined plane, with angle of inclination 𝜃=30𝑜, is moving down the incline at constant velocity. The work done by the friction force as the block moves 3.0 m along the incline is -30 J. What is the mass of the block? A) 1 kg B) 2 kg C) 3 kg D) 4 kg E) 0.5 kg
B. 2kg
2. Approximately how many pennies would you have to stack to reach an average 2 meter ceiling? a. 2x10^2 b. 2x10^3 c. 2x10^4 d. 2x10^5
B. 2x10^3
For general projectile motion, when the projectile is at the highest point of its trajectory: a. Its acceleration is zero. b. Its velocity is perpendicular to the acceleration c. Its velocity and acceleration are both zero d. The horizontal component of its velocity is zero e. The horizontal and vertical components of its velocity are zero
B. Its velocity is perpendicular to the acceleration.
. A 2.0 kg disk-like wheel, 0.3 m in radius, is rolled on a horizontal surface with translational kinetic energy of 16 J. The angular velocity is closest to: A) 6.5 rad/s B) 10.0 rad/s C) 13.3 rad/s D) 16.6 rad/s E) 20.0 rad/s
C) 13.3 rad/s
An object is given an initial velocity of 6.0 m/s. The coefficient of kinetic friction between the object and the surface it slides across is 0.050. How far will the object travel before coming to a stop? A) 19 m B) 25 m C) 37 m D) 57 m
C) 37 m
A 4-kg ball is released from rest near the earth's surface. At the moment it is released ... A) ball exerts more force on the earth than the earth does on the ball B) earth exerts more force on the ball than the ball does on the earth C) both exert the same amount of force on each other D) ball exerts no force on
C) both exert the same amount of force on each other
. A small planet having a radius of 1000 km exerts a gravitational force of 100 N on an object that is 500 km above its surface. If this object moved 500 km farther from the planet, the gravitational force on it would be closest to a. 75 N b. 71 N c. 56 N d. 50 N e. 25 N
C. 56
3. Car A with a mass of 2m is traveling west at a speed of v. Car B with a mass of m is traveling west at a speed of 2v. Both cars slam on their brakes at the same time, skidding to a stop. Assuming the coefficient of static friction between the wheels of the cars and the road is the same, which car travels farther while stopping? a. They travel the same distance b. Car A travels farther c. Car B travels farther d. Impossible to tell without knowing v e. Impossible to tell without knowing m
C. Car B travels farther
The forces shown in the force vs. time diagram in the figure below act on a 5-kg particle. What is the impulse for the interval from t = 0 to t = 4.0 s. A) 16 Ns B) 14 Ns C) 8 Ns D) 10 Ns
D) 10 Ns
A 2.0 kg box is initially at rest on a frictionless surface. A ball is thrown at the side of the box such that the ball is in contact with the box for 0.1 s before bouncing back. Afterwards the box is moving at 1.25 m/s What average force did the ball exert on the box? A) 12 N B) 34 N C) 45 N D) 25 N E) 63 N
D) 25 N
A tetherball is on a 2.1 m string that makes an angle of 44° with the vertical as it moves around the pole in a horizontal plane. If the mass of the ball is 1.3 kg and the tension in the string is 17.71 N, what is the ball's speed? A) 4.2 m/s B) 2.9 m/s C) 3.4 m/s D) 3.7 m/s
D) 3.7 m/s
At time t = 0 s, a wheel has an angular velocity of +28 rad/s. The wheel has a constant angular acceleration of -0.51 rad/s2. In this situation, the time t at which the wheel will have an angular velocity of zero is closest to: A) 120 s B) 130 s C) 96 s D) 78 s E) 55 s
E) 55 s
3. A counterclockwise net torque acts on a wheel. What can you say about its angular velocity? A) It is counterclockwise B) It is clockwise C) It doesn't exit D) It is okay E) It cannot be determined from the information provided
E) It cannot be determined from the information provided
You carry a 7 kg bag of groceries 1.2 m above the level floor at a constant velocity of 75 cm/s across a 2.3 m room. How much work do you do on the bag in the process? a. 0.0 J b. 82 J c. 158 J
a. 0.0
Two particles (m1 = 0.20 kg, m2 = 0.30 kg) are positioned at the ends of a 2.0-m long rod of negligible mass. What is the moment of inertia of this rigid body about an axis perpendicular to the rod and through the center of mass? a. 0.48 kg-m2 b. 0.50 kg-m2 c. 1.2 kg-m2 d. 0.80 kg-m2
a. 0.48 kg-m2
. A particle moves according to the following equation that describes its position (x) as a function of time (t). A, B, C, and D are constants. The units for time is the second and the units of the x is the meter. What is the unit of the constant B? 𝑥(𝑡)=(𝐴𝑡+𝐵)𝑡+𝐶 𝑡cos(𝜋𝑡)+𝐷 A) 𝑚/s B) 𝑚 C) s/m D) m/s2 E.m^2
a. M/s
A stock person at the local grocery store has a job consisting of the following five segments: (1) Picking up boxes of tomatoes from the stockroom floor vertically (2) Accelerating to a comfortable speed (3) Carrying the boxes to the tomato display at constant speed (4) Decelerating to a stop (5) Lowering the boxes slowly to the floor vertically During which of the five segments of the job does the stock person do zero work on the boxes? a. (1) and (5) b. (3) only c. (1), (2), (4),
b. (3)
When a rigid body rotates about a fixed axis, all the points in the body have the same a. Tangential speed b. Angular acceleration c. Tangential acceleration d. Linear displacement e. Centripetal acceleration
b. Angular acceleration
Two bodies P and Q on a smooth horizontal surface are connected by a light cord. The mass of P is greater than that of Q. A horizontal force F (of magnitude F) is applied to Q as shown in the figure, accelerating the bodies to the right. The magnitude of the force exerted by the connecting cord on body P will be a. zero. b. less than F but not zero. c. equal to F. d. greater than F. e. we do not have enough information to know
b. less than F but not zero.
Alice and Tom dive from an overhang into the lake below. Tom simply drops straight down from the edge, but Alice takes a running start and jumps with an initial horizontal velocity of 25 m/s. Neither person experiences any significant air resistance. Compare the time it takes each of them to reach the lake below. a) Alice reaches the surface of the lake first. b) Tom reaches the surface of the lake first. c) Alice and Tom will reach the surface of the lake at the same time. d) We need to know the height of the cliff before we can find this out e) We need to know
c) Alice and Tom will reach the surface of the lake at the same time.
An object of mass 2 kg has a constant velocity of 2 m/s in the negative x direction. What is the net force acting on it? A) 4 N B) -4 N C) 0 N D) Need more information
c. 0 N
16. A figure skater rotating at 5 rad/s with arms extended has a moment of inertia of 2.25 kg m2. If the arms are pulled in so that the moment of inertia decreases to 1.8 kg m2, what is the final angular speed of the figure skater? a. 2.25 rad/s b. 4.60 rad/s c. 6.25 rad/s d. 1.76 rad/s e. 0.810 rad/s
c. 6.25 rad/s
4. Suppose that a car traveling to the west (the -x direction) begins to slow down as it approaches a traffic light. Which statement concerning its acceleration in the x direction is correct? a. Both its acceleration and its velocity are positive b. Both its acceleration and its velocity are negative c. Its acceleration is positive but its velocity is negative d. Its acceleration is negative but its velocity is positive e. Nothing certain can be said about the relationship between its acceleration
c. Its acceleration is positive but its velocity is negative
A block slides down a 20o incline with a constant speed of 20 m/s, what is the net force on it? A) Twenty newtons to the right. B) Twenty newtons to the left. C) Zero newtons. D) We need to know the mass of the block
c. Zero newtons
A small glider is coasting horizontally when suddenly a very heavy piece of cargo falls out of the bottom of the plane. You can neglect air resistance. Just after the cargo has fallen out a. the plane speeds up and the cargo slows down. b. the plane speeds up but the cargo does not change speed. c. neither the cargo nor the plane change speed. d. the cargo slows down but the plane does not change speed. e. both the cargo and the plane speed up
c. neither the cargo nor the plane change speed.
A 4.5 kg wheel that is 34.5 cm in diameter rotates through an angle of 13.8 rad as it slows down uniformly from 22 rad/s to 13.5 rad/s. What is the magnitude of the angular acceleration of the wheel? a. 0.616 rad/s2 b. 5.45 rad/s2 c. 111 rad/s2 d. 22.5 rad/s2 e. 10.9 rad/s2
e. 10.9 rad/s2
rock is dropped from the top of a vertical cliff and takes 3 s to reach the ground below the cliff. A second rock is thrown vertically from the top of the cliff, and it takes this rock 2 s to reach the ground below the cliff from the time it is released. With what velocity was the second rock thrown, assuming no air resistance? a. 4.76 m/s upward b. 5.51 m/s downward c. 12.3 m/s upward d. 4.76 m/s downward e. 12.3 m/s downward
e. 12.3 m/s downward