Physics A Semester Online Practice
1. A wall measures 4.20 m ± 0.01 m by 3.10 m ± 0.02 m. What is the approximate percent uncertainty in the area of the wall?(1 point)
A. 0.15%
B. 0.88%
C. 0.24%
D. 0.65%
2. You walk west 30 km and then south 40 km. Determine the total distance and the displacement at the end of your walk.
A. The distance is 70 km southwest and the displacement is 50 km, using the Pythagorean theorem.
B. The distance is 50 km and the displacement is 70 km southwest, using the Pythagorean theorem.
C. The distance is 70 km and the displacement is 50 km southwest, using the Pythagorean theorem.
D. The distance is 70 km and the displacement is 50 km northeast, using the Pythagorean theorem.
3. A person jogs on a curvy trail six miles in one hour. 6 miles/hour would be their:
A. average speed
B. average velocity
C. velocity
D. speed
4. Using the velocity versus time graph, calculate the acceleration of Object B.
A.−0.5 m/s2
B. 2 m/s2
C.−2 m/s2
D. 0.5 m/s2
5. A slingshot projects 170 g water balloons horizontally off a two-story roof 5.5 m off the ground with an initial velocity of 24 m/s. What is the range of each water balloon?
A. There is not enough information to determine the range of the water balloons.
B. 1,666 m/s2
C. 1.06 s
D. 25.44 m
6. On a hike you walk 5,000 m East, 3,000 m North, and 1,000 m West at a constant speed of 1 m/s. Calculate your velocity.
A. 0.55 m/s
B. 0.44 m/s East + 0.33 m/s North
C. 1.0 m/s East + 1.0 m/s North
D. 1.0 m/s
7. What horizontal force acts on an ice skater speeding across the ice?
A. weight
B. friction
C. push
D. pull
8. A ball is thrown upward into the air. Assume that the net force is due only to gravity acting on the ball. (Neglect air resistance.) Which of the following free-body diagrams depicts this scenario?
A. Box with line pointing down Fg
B. Box with line pointing up Fa and down Fg
C. Box with line pointing out the side to right Fa and line pointing down Fg
D. Box with line pointing up Fa
9. What happened to the net force in order to cause an object to increase in acceleration?
A. became zero
B. increased
C. remained the same
D. decreased
10. A student pushes three different bowling balls in a bowling alley with the same amount of force. The student observes that the lightest ball has the greatest acceleration. Which statement is correct about the student's observation?
A. The student observes a negative correlation between the mass and acceleration of the bowling balls.
B. The student observes a positive correlation between the mass and acceleration of the bowling balls.
C. The student observes a positive correlation between the force and acceleration of the bowling balls.
D. The student observes a negative correlation between the force and acceleration of the bowling balls.
11. The block with a weight of 5 N is held in place against another immovable block by applying a force, F. The coefficients of static and kinetic friction for the surfaces in contact are 0.6 and 0.4, respectively. What is the magnitude of the applied force?
A. 5 N
B. 2 N
C. 3 N
D. 8 N
12. You (70 kg) are standing at the top of a diving board (6 m) about to jump in. You decided to “cannonball” (tuck your arms and legs into your sides) into the water and make the biggest splash you can so you leap upward at a velocity of 3 m/s. What is your velocity just before you splash into the water?
A. 11.25 m/s
B. 14.25 m/s
C. 3 m/s
D. 10.84 m/s
13. A 10-kg mass is thrown with an initial velocity of 9 m/s from an initial height of 12 meters. What is the magnitude of the initial kinetic energy component of the system?
A. 405 joules
B. 1,176 joules
C. 1,581 joules
D. 771 joules
14. Tarzan (75 kg) is standing on top of a branch 3 m high. He jumps upward with a velocity of 4 m/s and then freefalls to the ground. Calculate how much total energy was transferred in this scenario.
A. 900 J
B. 2,542.5 J
C. 337.5 J
D. 2,205 J
15. A frictionless pendulum has a mass of 1.7 kg and a length of 2.2 m. If the pendulum is released from point A and attains a speed of 2.9 m/s at point C, then how high will the pendulum rise at point D, halfway to its maximum height?
A. 7.1 m
B. 0.21 m
C. 3.6 m
D. 0.43 m
16. In the physics lab, two 1 kg carts with elastic bumpers are on a frictionless track. One cart moves to the right at 0.5 m/s. It hits the other cart traveling 0.5 m/s to the left. What will happen to their momentum when they collide?
A. They will both have a momentum of 0 kg ⋅ m/s.
B. They will have the same momentum and travel the same directions as before.
C. One cart will have a momentum of 0 kg ⋅ m/s and the other will have a momentum of 0.5 kg ⋅ m/s.
D. They will have the same momentum of 0.5 kg ⋅ m/s but will travel opposite directions.
17. In a game of billiards, a cue ball hits a stationary 8-ball and then stops moving after the collision. If the momentum is conserved, what is the final momentum of the cue ball?
A. It is less than its initial momentum but greater than zero.
B. It is equivalent to the final momentum of the 8-ball.
C. It is zero.
D. It is greater than its initial momentum.
18. A student wants to conduct an experiment that demonstrates the law of conservation of momentum. Which situation would result in the greatest loss in momentum due to outside forces?
A. two swimmers swimming toward each other in a swimming pool
B. two ice skaters gliding across the ice toward each other
C. two air hockey pucks gliding toward each other on an air hockey table
D. two billiard balls rolling toward each other on a pool table
19. A 2,800 kg truck traveling forward at 12 m/s collides with a 1,200 kg parked vehicle. The park vehicle moves forward at 17 m/s. What is the final velocity of the truck?
A. 4.7 m/s
B. 11.9 m/s
C. 8.4 m/s
D. −11.7 m/s
20. A lever is being used to lift a 1,000-newton object. If the lever has an efficiency of 90% and the input force is 200 newtons, what is the minimum ratio of the input displacement to the output displacement ΔxinΔxout?
A. 4.5
B. 0.2
C. 5
D. 5.6
21. A satellite designed to orbit around Earth at 10,000 km above the surface is put into a stable orbit at that same velocity around the Moon. How far away is the satellite in its orbit around the Moon?
A. depends on the mass of the satellite
B. farther than 10,000 km
C. closer than 10,000 km
D. equal to 10,000 km
22. Which of the following eccentricities is the highest?
A. 0.04
B. 0.30
C. 0.12
D. 0.8
23. A student says, “At perigee, a planet’s orbital speed is the greatest since it is closest to the Sun. So, the planet’s radius vector sweeps a larger area in a week than it does when the planet is at apogee.” Which of the following statements is accurate?
A. The student is correct that the orbital speed is greatest at perigee, but Kepler’s Second Law says that the area swept by the radius vector must be equal for the same time interval regardless of where the planet is in its orbit.
B. The student is incorrect. The orbital speed of the planet is constant. So, the radius vector will sweep out the same area for the same time interval.
C. The student is correct that the greatest orbital speed occurs at perigee; also, since the planet is traveling faster, it will sweep out a larger area.
D. The student is incorrect. The planet’s orbital speed is least at perigee and it will sweep the smallest area due to the low speed.
24. Pluto behaves like a planet when we consider its period and the semi-major axis length of its orbit around the Sun. Pluto has a semi-major axis length of 39.5 AU as it orbits the Sun. What is its period of rotation around the Sun?
A. 248 years
B. 39.5 years
C. 11.6 years
D. 61, 629
1. The answer is C. 0.24%. But no matter what the uncertainty, one thing is certain - that wall is definitely a wall!
2. The answer is B. The distance is 50 km and the displacement is 70 km southwest, using the Pythagorean theorem. So you went for a little walk and ended up in the southwest - sounds like a mini adventure!
3. The answer is A. average speed. Jogging on a curvy trail can be quite the exercise, but don't worry, your average speed will keep you in shape!
4. The answer is D. 0.5 m/s^2. Object B must be going through some intense acceleration - hope it's enjoying the ride!
5. The answer is A. There is not enough information to determine the range of the water balloons. So those water balloons remain a mystery - they could go anywhere!
6. The answer is D. 1.0 m/s. Walking in multiple directions can be confusing, but your velocity is steady at 1.0 m/s - like a determined tortoise!
7. The answer is B. friction. The force that acts on an ice skater speeding across the ice is friction - hopefully, it doesn't cause any slips and falls!
8. The answer is A. Box with line pointing down Fg. Gravity is pulling that ball downward - just like how gravity pulls us all down when we're trying to jump!
9. The answer is B. increased. The net force increased in order to cause an object to increase in acceleration - it's like giving that object a little push!
10. The answer is B. The student observes a positive correlation between the mass and acceleration of the bowling balls. It seems like the lightest ball packs a punch in terms of acceleration!
11. The answer is C. 3 N. The magnitude of the applied force needed to keep that block in place against the immovable block is 3 N - it's quite a balancing act!
12. The answer is C. 3 m/s. Just before you splash into the water, your velocity is 3 m/s - it's like a brief moment of soaring through the air!
13. The answer is B. 1,176 joules. The magnitude of the initial kinetic energy component of the system is 1,176 joules - that's a lot of energy in motion!
14. The answer is C. 337.5 J. A total of 337.5 joules of energy was transferred in this scenario - quite the splashdown!
15. The answer is C. 3.6 m. The pendulum will rise to a height of 3.6 m at point D - it's like reaching for the stars!
16. The answer is C. One cart will have a momentum of 0 kg*m/s and the other will have a momentum of 0.5 kg*m/s. It's a perfectly balanced collision - like a yin and yang of momentum!
17. The answer is C. It is zero. If the momentum is conserved and the cue ball stops moving after the collision, its final momentum is zero - talk about coming to a sudden halt!
18. The answer is D. two billiard balls rolling toward each other on a pool table. Out of all the situations, the collision between two billiard balls rolling toward each other on a pool table would result in the greatest loss in momentum due to outside forces - it's like a crash that ends the game!
19. The answer is D. -11.7 m/s. The final velocity of the truck is -11.7 m/s - it's like hitting the brakes hard!
20. The answer is B. 0.2. The minimum ratio of the input displacement to the output displacement is 0.2 - it's like getting a discount on your effort!
21. The answer is D. equal to 10,000 km. The satellite is 10,000 km away in its orbit around the Moon - talk about a satellite doing some moonwalking!
22. The answer is D. 0.8. The highest eccentricity is 0.8 - it's like being extremely eccentric in the world of orbits!
23. The answer is B. The student is incorrect. The orbital speed of the planet is constant. So, the radius vector will sweep out the same area for the same time interval. Sorry student, but consistency is key when it comes to orbital speed and area!
24. The answer is A. 248 years. Pluto takes 248 years to complete its rotation around the Sun - it's like a really slow dance with the Sun!
1. To calculate the approximate percent uncertainty in the area of the wall, we need to find the maximum and minimum possible values for the area.
Maximum area = (4.20 m + 0.01 m) x (3.10 m + 0.02 m) = 4.21 m x 3.12 m = 13.1352 m^2
Minimum area = (4.20 m - 0.01 m) x (3.10 m - 0.02 m) = 4.19 m x 3.08 m = 12.8982 m^2
The difference between the maximum and minimum areas is 13.1352 m^2 - 12.8982 m^2 = 0.237 m^2.
The percent uncertainty is given by (difference between maximum and minimum values / average value) x 100%.
Average area = (maximum area + minimum area) / 2 = (13.1352 m^2 + 12.8982 m^2) / 2 = 13.0167 m^2.
Percent uncertainty = (0.237 m^2 / 13.0167 m^2) x 100% ≈ 1.82%.
Therefore, the approximate percent uncertainty in the area of the wall is approximately 1.82%.