PHYS-91(part1): Multiple Choices and Short Answer question

1. For the hydrogen atom, which series describes electron transitions to the N=1 orbit, the lowest energy electron orbit? Is it the:

w) Lyman series

x) Balmer series

y) Paschen series

z) Pfund series

2. Electric current may be expressed in which one of the following units?

w) coulombs/volt

x) joules/coulomb

y) coulombs/second

z) ohms/second

4. A Newton is equal to which of the following?

w) kilogram-meter per second

x) meter per second squared

y) kilogram-meter per second squared

z) kilogram per meter-second

ANSWER: Y -- KILOGRAM-METER PER SECOND SQUARED

5. For an object moving in uniform circular motion, the direction of the instantaneous acceleration vector is:

w) tangent to the path of motion

x) equal to zero

6. A boy is standing on an elevator which is traveling downward with a constant velocity of 30 meters per second. The boy throws a ball vertically upward with a velocity of 10 meters per second relative to the elevator. What is the velocity of the ball, MAGNITUDE AND DIRECTION, relative to the elevator shaft the instant the boy releases the ball?

ANSWER: 20 METERS PER SECOND DOWN

7. Work is equal to which of the following?

w) the cross product of force and displacement.

x) the product of force times time

y) force divided by time

z) the dot product of force and displacement

ANSWER: Z -- THE DOT PRODUCT OF FORCE AND DISPLACEMENT

8. The work done by a friction force is:

w) always positive

x) always negative

y) always zero

z) either positive or negative depending upon the situation.

9. As defined in physics, work is:

w) a scalar quantity

x) always a positive quantity

y) a vector quantity

z) always zero

ANSWER: W -- A SCALAR QUANTITY

10. A pendulum which is suspended from the ceiling of a railroad car is observed to hang at an angle of 10 degrees to the right of vertical. Which of the following answers could explain this phenomena?

w) The railroad car is at rest.

x) The railroad car is accelerating to the left.

y) The railroad car is moving with constant velocity to the right.

z) The railroad car is accelerating to the right.

w) 16 newtons

x) 5 newtons

y) 9 newtons

z) 7 newtons

13. A boy throws a ball vertically upward with a velocity of 6 meters per second. How long does it take the ball to return to the boy's hand?

ANSWER: 1.22 SECONDS   (accept: 1.2 seconds)

14. A toy train moves in a circle of 8 meters radius with a speed of 4 meters per second. What is the magnitude of the acceleration of the train?

ANSWER: 2 METERS PER SECOND SQUARED

16. A box is initially at rest on a horizontal, frictionless table. If a force of 10 Newtons acts on the box for 3 seconds, what is the momentum of the box at the end of the 3 second interval?

ANSWER: 30 NEWTON-SECONDS or 30 KILOGRAM-METER PER SECOND

w) 1000

x) 3000

y) 5000

z) 7000

21. If the distance between two objects, each of mass 'M', is tripled, the force of attraction between the two objects is:

w) 1/2 the original force

x) 1/3 the original force

y) 1/9 the original force

z) unchanged

ANSWER: Y -- 1/9 THE ORIGINAL FORCE

22. A 40 kilogram girl climbs a vertical distance of 5 meters in twenty seconds at a constant velocity. How much work has the girl done?

ANSWER: 2000 JOULES or 1960 JOULES

24. In physics, a radian per second is a unit of:

w) angular displacement

x) angular velocity

y) angular acceleration

z) angular momentum.

w) increasing

x) decreasing

y) always zero

z) constant

w) Heisenberg

x) Bohr

y) Teller

z) Pauli

33. The force acting between two point charges can be computed using which of the following laws?

w) Ohm's Law

x) Ampere's Law

y) Coulomb's Law

z) Newton's Second Law.

34. Five volts are applied across the plates of a parallel plate capacitor. The distance of separation of the plates is .02 meters. What is the magnitude of the electric field inside the capacitor?

ANSWER: 250 VOLTS PER METER   or   250 NEWTONS PER COULOMB

w) Gauss's Law

y) Ohm's Law

z) Ampere's Law

38. For a negative point charge, the electric field vectors:

w) circle the charge

x) point radially in toward the charge

y) point radially away from the charge

z) cross at infinity

39. For an infinite sheet of positive charge, the electric field lines:

w) run parallel to the sheet of charge

x) are perpendicular to the sheet of charge and point in toward the sheet

y) are perpendicular to the sheet of charge and point away from the sheet

z) fall off as one over r squared

ANSWER: Y -- ARE PERPENDICULAR TO THE SHEET OF CHARGE AND POINT AWAY

40. Five coulombs of charge are placed on a thin-walled conducting shell. Once the charge has come to rest, the electric potential inside the hollow conducting shell is found to be:

w) zero

x) uniform inside the sphere and equal to the electric potential on the surface of the sphere

y) smaller than the electric potential outside the sphere

z) varying as one over r squared.

ANSWER: X -- UNIFORM INSIDE THE SPHERE AND EQUAL TO THE ELECTRIC OTENT

Questions