Tag Archives: A 20-kg crate is suspended from a fixed

Fundamental & Non-Fundamental Forces

18. Consider the following forces.

(1) frictional (2) gravitational (3) tension (4) strong nuclear (5) normal (6) electroweak

Which of the forces listed are considered fundamental forces?

1. A) 1, 2, and 4
2. B) 1, 2, 3, and 5
3. C) 1, 3, and 5
4. D) 2, 4, and 6
5. E) 2, 3, 4, and 6

Friction

A 2.0-N force acts horizontally on a 10-N block that is initially at rest on a horizontal surface.  The coefficient of static friction between the block and the surface is 0.50.

19. What is the magnitude of the frictional force that acts on the block?
20. A) 0 N
21. B) 2 N
22. C) 5 N
23. D) 8 N
24. E) 10 N

Fundamental & Non-Fundamental Forces

19. Suppose that the block now moves across the surface with constant speed under the action of a horizontal 3.0-N force. Which one of the following statements concerning this situation is false?
20. A) The block is not accelerated.
21. B) The net force on the block is zero newtons.
22. C) The frictional force on the block has magnitude 3.0 N.
23. D) The coefficient of kinetic friction between the block and the surface is 0.30.
24. E) The direction of the total force that the surface exerts on the block is vertically upward

Tension

21. A muscle builder holds the ends of a massless rope. At the center of the rope, a 7.9-kg ball is hung as shown.

What is the tension in the rope if the angle q in the drawing is 6.0°?

1. A) 960 N
2. B) 740 N
3. C) 370 N
4. D) 230 N
5. E) 150 N

Fundamental & Non-Fundamental Forces

22. A block of mass M is hung by ropes as shown. The system is in equilibrium.  The point O represents the knot, the junction of the three ropes.  Which of the following statements is true concerning the magnitudes of the three forces in equilibrium?
23. A)
24. B)
25. C)
26. D)
27. E)

 

22. A 20-kg crate is suspended from a fixed, horizontal beam by two vertical ropes. What is the approximate tension in each rope?
23. A) 10 N
24. B) 40 N
25. C) 100 N
26. D) 200 N
27. E) 390 N

Fundamental & Non-Fundamental Forces

Uniform Circular Motion

24. A ball moves with a constant speed of 4 m/s around a circle of radius 0.25 m. What is the period of the motion?
25. A) 1 s
26. B) 4 s
27. C) 7 s
28. D) 1 s
29. E) 2 s
30. The second hand on a watch has a length of 4.50 mm and makes one revolution in 60.00 s. What is the speed of the end of the second hand as it moves in uniform circular motion?
31. A) 42 × 10^–4 m/s
32. B) 67 × 10^–3 m/s
33. C) 71 × 10^–3 m/s
34. D) 71 × 10^–4 m/s
35. E) 36 × 10^–5 m/s

 

24. Approximately one billion years ago, the Moon orbited the Earth much closer than it does today. The radius of the orbit was only 24 400 km.   The orbital period was only 23 400 s.  Today, the average radius is 385 000 km; and the present period is 2.36 × 10⁶ s.  Assuming that the orbit of the Moon is circular, calculate the ratio of the speed of the Moon in its ancient orbit to the speed that it has today.
25. A) 8
26. B) 8
27. C) 2
28. D) 15
29. E) 39

Fundamental & Non-Fundamental Forces

27. A solar-powered car is traveling at constant speed around a circular track. What happens to the centripetal acceleration of the car if the speed is doubled?
28. A) The centripetal acceleration remains the same.
29. B) The centripetal acceleration increases by a factor of 2.
30. C) The centripetal acceleration increases by a factor of 4.
31. D) The centripetal acceleration is decreased by a factor of one-half.
32. E) The centripetal acceleration is decreased by a factor of one-fourth.

 

28. A ball is whirled on the end of a string in a horizontal circle of radius R at constant speed v. Complete the following statement: The centripetal acceleration of the ball can be increased by a factor of 4 by
29. A) keeping the speed fixed and increasing the radius by a factor of 4.
30. B) keeping the radius fixed and increasing the speed by a factor of 4.
31. C) keeping the radius fixed and increasing the period by a factor of 4.
32. D) keeping the radius fixed and decreasing the period by a factor of 4.
33. E) keeping the speed fixed and decreasing the radius by a factor of 4.

Fundamental & Non-Fundamental Forces

29. A rock is whirled on the end of a string in a horizontal circle of radius R with a constant period T. If the radius of the circle is reduced to R/3, while the period remains T, what happens to the centripetal acceleration of the rock?
30. A) The centripetal acceleration remains the same.
31. B) The centripetal acceleration increases by a factor of 3.
32. C) The centripetal acceleration increases by a factor of 9.
33. D) The centripetal acceleration decreases by a factor of 3.
34. E) The centripetal acceleration decreases by a factor of 9.

 

Newton’s Law of Gravitation (Chapter 13) Fundamental Force

 

30. Two point masses m and M are separated by a distance d. If the distance between the masses is increased to 3d, how does the gravitational force between them change?
31. A) The force will be one-third as great.
32. B) The force will be one-ninth as great.
33. C) The force will be three times as great.
34. D) The force will be nine times as great.
35. E) It is impossible to determine without knowing the numerical values of m, M, and d.

Fundamental & Non-Fundamental Forces

31. Two point masses m and M are separated by a distance d. If the separation d remains fixed and the masses are increased to the values 3m and 3M respectively, how does the gravitational force between them change?
32. A) The force will be one-third as great.
33. B) The force will be one-ninth as great.
34. C) The force will be three times as great.
35. D) The force will be nine times as great.
36. E) It is impossible to determine without knowing the numerical values of m, M, and d.

 

32. Which one of the following statements concerning the two “gravitational constants” G, the universal gravitational constant, and g the magnitude of the acceleration due to gravity is true?
33. A) The values of g and G depend on location.
34. B) The values of g and G do not depend on location.
35. C) The value of G is the same everywhere in the universe, but the value of g is not.
36. D) The value of g is the same everywhere in the universe, but the value of G is not.
37. E) The values of g and G are equal on the surface of any planet, but in general, G varies with location in the universe.

Fundamental & Non-Fundamental Forces

33. What is the magnitude of the gravitational force acting on a 79.5- g object due to a 580- kg object that is 2.40 m away?
34. A) 33 × 10^–9 N
35. B) 33 × 10^–8 N
36. C) 33 × 10^–10 N
37. D) 41 × 10^–7 N
38. E) 29 × 10^–8 N

 

34. Two objects are separated by a distance such that the gravitational force between them is 6.673 nN. If both objects have a mass of 1 Mg, what is the distance between them?

A)1 meter

1. B) 10 meters.
   C) 100 meters.
   D)1000 meters.
2. The correct answer is not given

Fundamental & Non-Fundamental Forces

35. If the moon were half as far from the earth as it is now, the gravitational force it exerts on the earth would be
    A)one-quarter its present value.
    B) half its present value.
    C) twice its present value.
    D)four times its present value.
36. None of the above is correct

 

36. Mars is about 1.5 times as far from the sun as the earth and its mass is about 0.1 times the earth’s mass. Relative to the gravitational force the sun exerts on the earth, the force it exerts on Mars is about
    A) 0.0044 as much.
    B) 0.0067 as much.
    C)0.44 as much.
    D) 0.067 as much.
37. E) The correct answer is not given.

 

37. A woman whose mass is 60 kg on the earth’s surface is in a spacecraft at a height of 2 earth radii above the earth’s surface. Her mass there is
    A) 6.7 kg.
    B) 15 kg.
    C) 20 kg.
    D) 60 kg.
38. E) 588 kg.

 

38. A man whose mass is 80 kg on the earth’s surface is in a spacecraft at a height of 2 earth radii above the earth’s surface. His weight there is
    A)970 N.
    B) 800 N.
    C) 97 N.
    D) 87 N.
39. E) 55 N.

APA.