Test Bank For PHYSICS FOR SCIENTISTS AND ENGINEERS 9TH EDITION BY SERWAY

Test Bank For PHYSICS FOR SCIENTISTS AND ENGINEERS 9TH EDITION BY SERWAY

Chapter 8—Conservation of Energy

MULTIPLE CHOICE

1. A single conservative force F_x = (6.0x – 12) N (x is in m) acts on a particle moving along the x axis. The potential energy associated with this force is assigned a value of +20 J at x = 0. What is the potential energy at x = 3.0 m?

ANS:  B                    PTS:   2                    DIF:    Average

2. As a particle moves along the x axis it is acted upon by a single conservative force given by F_x = (20 – 4.0x) N where x is in m. The potential energy associated with this force has the value +30 J at the origin (x = 0). What is the value of the potential energy at x = 4.0 m?

ANS:  C                    PTS:   2                    DIF:    Average

3. A 0.40-kg particle moves under the influence of a single conservative force. At point A where the particle has a speed of 10 m/s, the potential energy associated with the conservative force is +40 J. As the particle moves from A to B, the force does +25 J of work on the particle. What is the value of the potential energy at point B?

ANS:  B                    PTS:   2                    DIF:    Average

4. As a 1.0-kg object moves from point A to point B, it is acted upon by a single conservative force which does -40 J of work during this motion. At point A the speed of the particle is 6.0 m/s and the potential energy associated with the force is +50 J. What is the potential energy at point B?

ANS:  C                    PTS:   2                    DIF:    Average

5. A 12-kg block on a horizontal frictionless surface is attached to a light spring (force constant = 0.80 kN/m). The block is initially at rest at its equilibrium position when a force (magnitude P = 80 N) acting parallel to the surface is applied to the block, as shown. What is the speed of the block when it is 13 cm from its equilibrium position?

ANS:  A                    PTS:   2                    DIF:    Average

6. A 7.0-kg block on a horizontal frictionless surface is attached to a light spring (force constant = 1.2 kN/m). The block is initially at rest at its equilibrium position when a force of magnitude P acting parallel to the surface is applied to the block, as shown. When the block is 8.0 cm from the equilibrium position, it has a speed of 0.80 m/s. How much work is done on the block by the force P as the block moves the 8.0 cm?

ANS:  C                    PTS:   2                    DIF:    Average

7. A 0.60-kg object is suspended from the ceiling at the end of a 2.0-m string. When pulled to the side and released, it has a speed of 4.0 m/s at the lowest point of its path. What maximum angle does the string make with the vertical as the object swings up?

ANS:  B                    PTS:   3                    DIF:    Challenging

8. A pendulum is made by letting a 2.0-kg object swing at the end of a string that has a length of 1.5 m. The maximum angle the string makes with the vertical as the pendulum swings is 30°. What is the speed of the object at the lowest point in its trajectory?

ANS:  A                    PTS:   2                    DIF:    Average

9. A 2.0-kg mass swings at the end of a light string (length = 3.0 m). Its speed at the lowest point on its circular path is 6.0 m/s. What is its kinetic energy at an instant when the string makes an angle of 50° with the vertical?

ANS:  B                    PTS:   3                    DIF:    Challenging

10. A 2.5-kg object suspended from the ceiling by a string that has a length of 2.5 m is released from rest with the string 40° below the horizontal position. What is the tension in the string at the instant when the object passes through its lowest position?

ANS:  C                    PTS:   3                    DIF:    Challenging