Test 2

1. State Newton's second law.

A. Any two objects in the universe attract each other with a force directly proportional to the product of their masses and inversely proportional to the square of the distance separating them.
B. The force acting on an object is inversely proportional to the acceleration produced by the force.
C. An object will remain at rest or move in a straight line with a costant speed unless acted upon by a net force.
D. For every reaction, there is an equal but opposite reaction.
E. The force acting on an object is directly proportional to the acceleration produced by the force.

2. Mass of an object is ...

A. measured in terms of Newtons.
B. the same as the weight of the object.
C. a measure of the gravitational force exerted on the object by the massive object in the vicinity of the object.
D. a measure of the amount of matter the object has.
E. different on different planets.

3. A force that causes an acceleration of 4 m ⁄ s ² on an object of mass 12.324 kg is acting on a 48 kg object. Calculate the acceleration of the 48 kg object.

A. 1.8 m ⁄ s ²
B. 0.327 m ⁄ s ²
C. 0.595 m ⁄ s²
D. 1.027 m ⁄ s ²
E. 1.356 m ⁄ s²

4. Which of the following is not a correct statement?

A. The force required to just get an object slding is bigger than the force required to slide it once it has started sliding.
B. Static coefficient of friction is greater than kinetic coefficient of friction
C. Coefficient of friction is equal to the ratio of normal force to force of friction.
D. Coefficient of friction is unit less.
E. If normal frorce is doubled, force of friction will be doubled.

5. An object of mass 56.666 kg is sliding on a horizontal surface. Calculate the normal force exerted by the surface on the object.

A. 462.025 N
B. 612.169 N
C. 981.302 N
D. 341.458 N
E. 555.327 N

6. An object of mass 27.764 kg is being pulled by a horizontal force of 270 N on a horizontal force. The coefficient of kinetic friction between the object and the surface is 0.45. Calculate the 6.276 m ⁄ s₂acceleration of the object.

A. 6.276 m ⁄ s²
B. 0.721 m ⁄ s²
C. 7.73 m ⁄ s²
D. 5.315 m ⁄ s²
E. 3.732 m ⁄ s²

7. An object of mass 500 kg is hanging from a ceiling by means of two strings. The first string ( T₁ ) makes an angle of 25 degree with the horizontal-right. The second string ( T₂) makes an angle of 35 degree with the horizontal-left. The equations relating the x-components and the y-components of the forces acting on the object respectively are

A. -0.906 * T₁ + 0.574 * T₂ = 0
-0.906 * T₁ + 0.574 * T₂ - 4900 N = 0
B. -0.906 * T₁ + 0.819 * T₂ = 0
0.423 * T₁ + 0.574 * T₂ - 4900 N = 0
C. 0.423 * T₁ + 0.574 * T₂ - 4900 N = 0
-0.906 * T₁ + 0.819 * T₂ = 0
D. -0.906 * T₁ + 0.819 * T₂ - 4900 N = 0
0.423 * T₁ + 0.574 * T₂ = 0
E. 0.423 * T₁ + 0.574 * T₂ = 0
-0.906 * T₁ + 0.819 * T₂ - 4900 N = 0

8. An object of mass 90 kg is being pulled on a friction less horizontal surface by means of a string that makes an angle of 60 degree with the horizontal. If the tension in the string is 100 N calculate the acceleration of the object.

A. 0.556 m ⁄ s ²
B. 1.925 m ⁄ s²
C. 0.962 m ⁄ s²
D. 9.8 m ⁄ s ²
E. 1.111 m ⁄ s ²

9. An object of mass 10 kg is being pulled on a horizontal surface by a string that makes an angle of 70 degree with the horizontal. The tension in the string is 16 N. Calculate the normal force exerted by the ground on the object.

A. 138.071 N
B. 118.738 N
C. 82.965 N
D. 38.427 N
E. 61.601 N

10. An object of mass 24 kg is sliding down a friction less inclined plane that makes an angle of 60 deg with the horizontal. Calculate the component of gravitational force that pushes the object against the plane in a direction perpendicular to the inclined plane.

A. 235.2 N
B. 117.6 N
C. 203.689 N
D. 4.9 N
E. 8.487 N

11. SI unit of work expressed in terms of fundamental units of mechanics is equal to...

A. Newton * meter
B. kilogram * meter ⁄ second²
C. kilogram * meter ² ⁄ second
D. kilogram * meter ² ⁄ second ²
E. kilogram * meter ⁄ second

12. An object is displaced by a distance of 10 m horizontally by a 600 force that makes an angle of 80 deg with the horizontal. Calculate the wrk done by the force.

A. 718.094 J
B. 1972.966 J
C. 334.035 J
D. 1041.889 J
E. 1429.436 J

13. A 5 kg object is displaced to the right by a distance of 10 m under the influence of the following forces: a 30 N vertical force pushing on the object downwards, a 2 N force that makes an angle of 30 deg with the horizontal-right. Calculate the net work done on the object.

A. 17.321 J
B. 21.236 J
C. 4.916 J
D. 7.715 J
E. 26.303 J

14. Which of the following statements is correct.

A. The potential energy of an object depends on the speed of the object.
B. The work done by a conservative force depends on the path followed.
C. The work done by a conservative force is equal to the change in the kinetic energy of the object.
D. The work done by a conservative force is equal to the negative of the change in potential energy of the object.
E. Friction is a conservative force.

15. An object is displaced 17 m by a 54 N conservative force that makes an angle of 40 deg with the displacement. Calculate the change in its potential energy.

A. 703.229 J
B. 914.197 J
C. -703.229 J
D. -914.197 J
E. -562.583 J

16. Under the influence of conservative forces only, an object is displaced from point A to point B. Its potential energy and kinetc energy at point A are respectively 64.343 J and 20.654 J. Its kinetic energy at point B is 25 J. Calculate its potential energy at point B.

A. 59.997 J
B. 106.777 J
C. 74.316 J
D. 9.548 J
E. 35.801 J

17. An object of mass 8.222 kg is located at the top of a 12 m tall building. Calculate the gravitational potential energy of the object with respect to a point 2 m below the top of the building.

A. 140.916 J
B. 161.151 J
C. 218.701 J
D. 114.503 J
E. 241.443 J

18. A roller coaster extends to the ground from a height of 30 m (point A) and then rises to a height of 13 m (point B). An object of mass 16 kg starts at point A with a speed of 7 m ⁄ s. Assuming the roller coaster is friction less, calculate the speed of the object by the time it reaches point B.

A. 23.188 m ⁄ s
B. 19.55 m ⁄ s
C. 31.371 m ⁄ s
D. 13.294 m ⁄ s
E. 26.424 m ⁄ s

19. Calculate the elastic potential stored by a spring of Hook's constant 400 N ⁄ m when it is compressed by 0.15 m.

A. 4.5 J
B. 0 J
C. 6.864 J
D. 5.403 J
E. 8.493 J

20. If all the forces acting on an object are conservative, then...

A. the mechanical energy of the object is conserved.
B. the change in kinetic energy is equal to the change in potential energy
C. the potential energy of the object is conserved
D. the work done is equal to the change in the mechanical energy of the object.
E. the kinetic energy of the object is conserved

21. An object of mass 0.045 kg released from a height of 12 m has a speed of 7 m ⁄ s just before it hits the ground. Calculate the work done by air resistance.

A. 0 J
B. -4.19 J
C. -6.312 J
D. 0.1 J
E. -3.397 J

22. Calculate the speed of an object of mass 0.36 kg moving with a momentum of 4.2 kg m ⁄ s.

A. 19.429 m ⁄ s
B. 2.282 m ⁄ s
C. 15.722 m ⁄ s
D. 11.667 m ⁄ s
E. 13.704 m ⁄ s

23. A object of mass 0.275 kg moving to the right with a speed of 19 m ⁄ s hits a wall and bounces back to the left with a speed of 7 m ⁄ s. Calculate the change in its momentum.

A. -12.282 kg m ⁄ s
B. -7.15 kg m ⁄ s
C. -10.177 kg m ⁄ s
D. -5.357 kg m ⁄ s
E. -8.389 kg m ⁄ s

24. An object was acted upon by a force of 15 for 1 seconds. Calculate the change in its momentum.

A. 3.858 kg m ⁄ s
B. 15 kg m ⁄ s
C. 23.551 kg m ⁄ s
D. 20.249 kg m ⁄ s
E. 26.863 kg m ⁄ s

25. An object of mass 12 kg moving with a speed of 24 m ⁄ s to the right collides with an object of mass 21 kg moving with a speed of 6 m ⁄ s to the left. After collision, the 21 kg object moves to the right with a speed of 5 m ⁄ s to the right. Calculate the velocity of the 12 kg object after collision.

A. 8.977 m ⁄ s
B. 4.75 m ⁄ s
C. 7.853 m ⁄ s
D. 3.42 m ⁄ s
E. 1.297 m ⁄ s

26. An object of mass 20 kg moving with a speed of 26 m ⁄ s to the right collides with an object of mass 11 kg at rest. If the collision is completely inelastic, calculate the kinetic energy lost during the collision.

A. -3693.817 J
B. -4399.711 J
C. -1588.597 J
D. -302.863 J
E. -2398.71 J

27. If a collision is a completely inelastic collision, then...

A. the kinetic energy of the colliding objects remains the same after collision.
B. after collision, the colliding objects will move in opposite directions.
C. the kinetic energy of the colliding objects increases during the collision.
D. the speeds after collision remain the same with the speeds before collision
E. the colliding objects will have the same velocity after collision

28. After a bullet of mass 0.035 kg is fired into a ballistic pendulum of mass 2.5 kg, the bullet is embedded in the pendulum and the pendulum rose to a height of 0.45 m. Calulate the speed with which the bullet was fired into the ballistic pendulum.

A. 343.778 m ⁄ s
B. 153.889 m ⁄ s
C. 215.102 m ⁄ s
D. 42.865 m ⁄ s
E. 404.525 m ⁄ s

29. An object of mass 13 kg going to the right with a speed of 27 m ⁄ s collides with a(n) 12 kg object at rest. If the collision is completely elastic, calculate the speed of the 12 kg object after collision.

A. 19.881 m ⁄ s
B. 5.36 m ⁄ s
C. 28.08 m ⁄ s
D. 31.296 m ⁄ s
E. 45.394 m ⁄ s

30. An object of mass 5 kg going to the right with a speed of 28 m ⁄ s collides with a(n) 4 kg object at rest. After collision the 5 kg object moves with a speed of 15 m ⁄ s making an angle of 70 degree with the horizontal-right. Calculate the y-component of the velocity of the 4 kg object after collision.

A. -20.626 m ⁄ s
B. -12.973 m ⁄ s
C. -31.021 m ⁄ s
D. -17.619 m ⁄ s
E. -9.465 m ⁄ s

Test 2: