Physics Final 2015

A small cart of mass M is initially at rest. It collides elastically with a large cart of mass 4M and velocity v. The large cart loses half its kinetic energy to the little cart. The little cart now has a velocity of

1.41v

Two traveling waves of equal frequency, one of amplitude 4 cm and the other of amplitude 6 cm, superimpose in a single medium. Which of the following best describes the displacement, D, of the resultant wave?

2 cm < D < 10 cm

If each of the resistors in the circuit has a resistance of 3 ohms, what must be the emf of the battery if the circuit draws a total current of 3 A?

30 V

What is the voltage drop across R3 in the circuit diagrammed above?

30 V

At a distance of 20 m from a source of sound, the sound level is 40 dB. If the observer backs up to a distance of 40 m from the source, what will the sound level b? (assume no absorption nor reflection of sound).

34 dB

A string fixed at both ends, supports a standing wave with a total of 4 nodes. If the length is 6 m, what is the wavelength?

4 m

If L, M, and T denote the dimensions of length, mass, and time, respectively, what are the dimensions of power?

ML^2/T^3

A mass on a spring and a simple pendulum undergo simple harmonic motion. There is no friction present for the mass on the string. Which of the following statements are true? Select two answers.

Mechanical energy is constant & the period of the mass is constant

An object (mass=m) above the surface of the Moon (mass=M) is dropped from an altitude h equal to the Moon's radius (R). What is the object's impact speed?

square root of GM/R

Two objects, A and B, have equal charge and equal mass. Neither body is in motion because the gravitational and electrostatic forces between them are equal. If the mass of Object A is halved, equilibrium will be maintained if

the charge on Object B were halved.

In the graph above, the instantaneous velocity at 9 seconds is closest to

-11/4 m/s

What is the power developed by the force?

0

What is the net work done as the mass falls from 0 to 8 cm?

0 J

A simple harmonic oscillator has a frequency of 2.5 Hz and an amplitude of 0.05 m. What is the period of the oscillations?

0.4 s

How much current does a 60 W light bulb draw if it operates at a voltage of 120 V?

0.5 A

Three resistors are connected to a 1.0 V battery, as shown in the diagram above. What is the current through the 2.0 ohm resistor?

0.50 A

In the figure above, the coeffecient of sliding friction between the small block and the tabletop is 0.2. If the pulley is frictionless and massless, what will be the acceleration of the blocks once they are released from rest?

0.7 g

If the rod in the figure above is uniform and has mass m, what is the tension in the supporting string? The rod is free to rotate about point P.

1/2mg

For the circuit shown above, what is the voltage of the battery (assuming the battery has no internal resistance)?

10 V

If the surface of the incline is frictionless with what speed will the block reach the bottom if it was released from rest at the top?

10 m/s

An object of mass 5 kg is acted upon by exactly four forces, each of magnitude 10 N. Which of the following could NOT be the resulting acceleration of the object?

10 m/s^2

An elevator has a mass of 500 kg. It may safely carry an additional mass of 1000 kg and accelerate upward at 2 m/s^2. What is the tension in the cable under these maximum conditions?

18,000 N

What is the maximum velocity of the mass?

2 m/s

If the coefficient of friction between the block and the incline is 0.4, how much work is done by the normal force on the block as it slides down the full length of the incline?

2.0 J

IF the surface of the incline is frictionless, how long will the block take to reach the bottom if it was released from rest at the top?

2.0 s

A crane lifts a shipping crate that weighs 5000 N at a constant speed of 4 m/s. At what rate is this crane doing work on the crate?

20,000 W

A car slows down on a highway. Its engine is providing a forward force of 1000 N; the force of friction is 3000 N. It takes 20 s for the car to come to rest. What is the car's change in momentum during these 20 s?

40,000 kgm/s

An astronaut lands on a planet whose mass and radius are each twice that of Earth. If the astronaut weighs 800 N on Earth, how much will he weigh on this planet?

400 N

A spring of force constant 800 N/m is hung from a ceiling. A block of mass 4.0 kg is hung from its lower end and allowed to come to rest. How far will the block stretch the spring?

5.0 cm

A tube with one end closed and one end open resonates for a wave with wavelength λa as shown. The next shorter wavelength at which resonance will occur is λb. The ratio of these two wavelengths λa/λb is

5/3

What is the wavelength of a 5 hz wave traveling with a speed of 10 m/s?

50

An electric dipole consists of a pair of equal but opposite point charges of magnitude 4.0 nC separated b a distance of 2.0 m. What is the electric field strength at the midway between the charges?

7.2 x 10^5 N/C

A .30-kg bird is flying from right to left at 30 m/s. The bird collides with and sticks to a 0.50-kg ball which is moving straight up with speed 6.0 m/s. What is the magnitude of the momentum of the ball/bird combination immediately after collision?

9.5 Ns

The electric field strength is a vacuum at a point at which distance from a source charge is NOT dependent on which of the following? Select two answers.

Another charge placed at that point & the sign of the source charge

The figure above shows a plane diagram. The figure shows four point charges arranged at the corners of a square with point B as its center. A positive charge would experience no net force if it were placed at which of the three points shown in the figure

B only

In which of the following situations involving a source of sound and detector of the sound is it possible that there is NO perceived Doppler shift?

Both the source and detector travel in the same direction.

Which of the following changes to a circuit will always bring about an increase in the current?

Increased voltage and decreased resistance

Sound waves travel at 350 m/s through warm air and at 3500 m/s through brass. What happens to the wavelength of a 700 Hz acoustic wave as it enters brass from warm air?

It increases by a factor of 10

What happens to the force of gravitational attraction between two small objects if the mass of each object is doubled and the distance between their centers is doubled?

It remains the same

Which of the following relates Pb, the rate at which energy is dissipated by resistor b, and Pe, the rate at which energy is dissipated by resistor e?

Pe=9Pb

Wire Y is made of the same material but has twice the diameter and half the length of Wire X. If Wire X has a resistance of R then Wire Y would have a resistance of

R/8

If the acceleration of an object is not zero, then which of the following could be constant? Select two answers.

Speed and kinetic energy

A musician plucks a string on an acoustic guitar. Standing waves will most likely occur in which of the following media? Select two answers.

The guitar string & the air inside the guitar

A lightweight toy car crashes head-on into a heavier toy truck. Which of the following statements is true as a result of the collision? Select two answers.

The magnitude of the acceleration experienced by the car will be greater than that experienced by the truck & the total momentum in the collision will be conserved.

A uniform bar is lying on a flat table. Besides the gravitational and normal forces (which cancel), the bar is acted upon by two other forces, F1 and F2, which are parallel to the surface of the table. If the net force on the rod is zero, then which one of the following is true?

The net torque will be zero if F1 and F2 are applied at the same point.

A simple pendulum executes simple harmonic motion as it swings through small angles of oscillation. If theta max denotes the amplitude of the oscillations, which of the following statements is true?

When theta=0, the tangential acceleration is 0

An alarm whose frequency is 400 Hz is dropped out of a third-floor window. The student who drops it measures the frequency with a very sensitive oscilloscope. The measured frequency

appears lower than 400 Hz and the frequency decreases as it falls

The figure above shows two positively charged particles. The +Q charge is fixed in position, and the +q charge is brought close to +Q and released from rest. Which of the following graphs best depicts the acceleration of the +q charge as a function of its distance r from +q?

curved, decreasing graph

Two charges are placed as shown at the vertices of an equilateral triangle. What is the direction of the electric field at point P?

d

Which of the following quantities is NOT a vector?

electric potential

If a charge of +q is placed at point P, the electric field at point P would

remain the same

A beam of monochromatic light entering a glass window pane the air will experience a change in

speed and wavelength

What is the period of the stopper?

square root of 4(pi)^2MR/F

Two people, one of mass 100 kg and the other of mass 50 kg, stand facing each other on an ice-covered (essentially fricitionless) pond. If the heavier person pushes on the lighter one with a force F, then

the magnitude of the acceleration of the lighter person will be twice the magnitude of the acceleration of the heavier person