**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

**ANSWER**: W -- LYMAN 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

**ANSWER**: Y -- COULOMBS/SECOND

**3. In the SI system of measure, what is the unit of capacitance?**

**ANSWER**: FARAD

**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

y) directed radially outward

z) directed radially inward

**ANSWER**: Z -- DIRECTED RADIALLY INWARD

**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.

**ANSWER**: X -- ALWAYS NEGATIVE

**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.

**ANSWER**: X -- THE RAILROAD CAR IS ACCELERATING TO THE LEFT.

**11. Two forces have magnitudes of 11 newtons and 5 newtons. The magnitude of their sum could NOT be equal to which of the following values?**

w) 16 newtons

x) 5 newtons

y) 9 newtons

z) 7 newtons

**ANSWER**: X -- 5 NEWTONS

**12. A ball leaves a girl's hand with an upward velocity of 6 meters per second. What is the maximum height of the ball above the girl's hand?**

**ANSWER**: 1.8 METERS

**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

**15. A certain machine exerts a force of 200 newtons on a box whose mass is 30 kilograms. The machine moves the box a distance of 20 meters along a horizontal floor.**

**What amount of work does the machine do on the box?**

**ANSWER**: 4000 JOULES

**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

**17. A block of metal which weighs 60 newtons in air and 40 newtons under water has a density, in kilograms per meter cubed, of:**

w) 1000

x) 3000

y) 5000

z) 7000

**ANSWER**: X -- 3000

**18. A 10 kilogram body initially moving with a velocity of 10 meters per second makes a head-on collision with a 15 kilogram body initially at rest. The two objects stick together. What is the velocity of the combined system just after the collision?**

**ANSWER**: 4 METERS PER SECOND

**19. A certain spring is known to obey Hooke's Law. If a force of 10 newtons stretches the spring 2 meters, how far will a 30 newton force stretch the spring?**

**ANSWER**: 6 METERS

**20. A helicopter is ascending vertically with a constant speed of 6 meters per second relative to the ground. At the instant the helicopter is 60 meters above the ground it releases a package. What is the magnitude and direction of the velocity of the package, relative to the ground, the instant the package is released by the helicopter?**

**ANSWER**: 6 METERS/SECOND UP

**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

**23. A machine performs 8 Joules of work in 2 seconds. How much power is delivered by this machine?**

**ANSWER**: 4 WATTS

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

w) angular displacement

x) angular velocity

y) angular acceleration

z) angular momentum.

**ANSWER**: X -- ANGULAR VELOCITY

**25. If the resultant force acting on a body of constant mass is zero, the body's momentum is:**

w) increasing

x) decreasing

y) always zero

z) constant

**ANSWER**: Z -- CONSTANT

**26. What is the name of the first American physicist to win two Nobel prizes?**

**ANSWER**: (JOHN) BARDEEN

**27. Which of the following scientists is responsible for the exclusion principle which states that two objects may NOT occupy the same space at the same time? Was it:**

w) Heisenberg

x) Bohr

y) Teller

z) Pauli

**ANSWER**: Z -- PAULI

**28. Who shared the Nobel Prize in Physics in 1909 with Guglielmo Marconi for his contribution to the development of wireless telegraphy?**

**ANSWER**: (CARL FERDINAND) BRAUN

**29. Who first theoretically predicted the existence of the positron, a positively charged electron? He received the Nobel Prize in Physics in 1933.**

**ANSWER**: (PAUL ADRIEN MAURICE) DIRAC

**30. Name the female physicist who received the Nobel Prize in 1963 for her discovery concerning the shell structure of the nucleus.**

**ANSWER**: (MARIA GOEPPERT) MAYER

**31. The constant potential difference across a 2 ohm resistor is 20 volts. How many watts of power are dissipated by this resistor?**

**ANSWER**: 200 WATTS

**32. The potential difference across a 4 ohm resistor is 20 volts. Assuming that all of the energy dissipated by this resistor is in the form of heat, how many joules of heat are radiated in 10 seconds?**

**ANSWER**: 1000 JOULES

**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.

**ANSWER**: Y -- COULOMB'S 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

**35. Used normally, a 150-watt, 120 volt light bulb requires how many amps of current?**

**ANSWER**: 1.25 AMPS

**36. If 10 joules of energy are required to move 5 coulombs of charge between two points, the potential difference between the two points is equal to how many volts?**

**ANSWER**: 2 VOLTS

**37. Induced electric currents can be explained using which of the following laws?**

w) Gauss's Law

x) Faraday's Law

y) Ohm's Law

z) Ampere's Law

**ANSWER**: X -- FARADAY'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

**ANSWER**: X -- POINT RADIALLY IN TOWARD THE CHARGE

**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