• Describe in detail two modern applications of electromagnets. Do these electromagnets draw a large amount of current or a little? How do you know? What supplies that current?
• Why do you think electromagnets are used in these different ways?
• What is the advantage of using an electromagnet rather than a permanent magnet?

A ball thrown straight up into the air is found to be moving at 7.24 m/s after falling 2.27 m below its release point. Find the ball's initial speed. Thank you.

Determine the order in which the following objects released from the same height, initially at rest and rolling down an incline without slipping, will reach the bottom: A hollow sphere, a solid sphere, a hollow pipe, and a solid cylinder.

Please explain in simplest terms and give an example using units given.

A diver springs upward from a board that is 3.09 meters above the water. At the instant she contacts the water her speed is 8.52 m/s and her body makes an angle of 71.8° with respect to the horizontal surface of the water. Determine her initial velocity.

What are some spacecraft that aim to study how our Solar System was formed? What studies did each spacecraft conduct?

A 16 g ball is fired horizontally with speed v0 toward a 111 g ball hanging motionless from a 0.9-m-long string. The balls undergo a head-on, perfectly elastic collision, after which the 111 g ball swings out to a maximum angle θmax=53°. What was v0?

Two point charges, -62.5 microcoulombs (placed on the left side of the positive charge) and +12.5 microcoulombs, fixed on the x-axis, are seperated by a distance of 25.0 cm from each other. At what points along the x-axis is the electric potential equal to zero? (A well-labeled sketch showing these points is required Find the voltage at a point on the x-axis, 15.0 cm to the left of the negative charge.

Two parallel electrical conducturs each leads a current of the same size. The distance between the center of the conductors can be varied from 100 mm to 1000 mm. The currents are going in the same directions in both of the conductors and have a value of I=19 A.

1. Calculate the force per meter (F/l) between the conductors in their plane and plot F/l against the distance between them (100 mm to 1000 mm) in a graph. Do not take to few points.
2. Show if there is a repelling or attractive force between the conductors.

Which of the following statements are true about relativistic mass, momentum and energy?

T or F? according to Einstein, a particle at rest has no energy at all

T or F? if a particle of rest mass m0 were entirely converted into energy, it would yield an energy of (m0)(c^2)

T or F? if it were possible to accelerate a particle near the speed of light, its relativistic mass would approach infinity

T or F? the relativistic expression for kinetic energy is the same as the classical (non-relativistic) equation for kinetic energy

T or F? when a particle moves at high speed, its relativistic mass is the same as its rest mass

A certain ultrasound device can measure a fetal heart rate as low as 50 beats per minute. This corresponds to the surface of the heart moving at about 4.0 x 10-4 m/s. If the probe generates ultrasound that has a frequency of 2.0 MHz (1 MHz = 1 megahertz = 106 Hz), what frequency shift must the machine be able to detect? Use v sound = 1540 m/s for the speed of sound in human tissue.

On Myth Busters it was determined that a penny dropped from the top of the Empire State Building would reach a terminal velocity of 64.4 miles per hour before hitting the ground. What is the height of the building in feet needed for a penny with a mass of 2.5 grams to reach a velocity of 46.7 miles per hour? Assume that no energy is lost from frictional drag. For the acceleration of gravity on the Earth us 9.81 meters per second squared or 32.2 feet per second squared.

In procedure 2: suppose red light passes through a double slit and falls on a screen. In the diffraction pattern, the distance from the central maximum to the first maximum is 5 mm.

a) The distance from the first minimum (dark spot) to the second minimum in the diffraction pattern is

between 7.5 mm and 10 mm

less than 2.5 mm    

more than 10 mm

between 2.5 mm and 5 mm

exactly 2.5 mm

between 5 mm and 7.5 mm

exactly 5 mm

exactly 7.5 mm

exactly 10 mm

b) Blue light has a higher frequency than red light. If you switch the light falling on the double slit from red to blue

the distance between the maxima decreases, the number of maxima on the screen remains the same

the distance between the maxima increases, the number of maxima on the screen decreases    

the distance between the maxima increases, the number of maxima on the screen increases

the distance between the maxima decreases, the number of maxima on the screen decreases

the distance between the maxima remains the same, the number of maxima on the screen increases

the distance between the maxima remains the same, the number of maxima on the screen remains the same

the distance between the maxima decreases, the number of maxima on the screen increases

the distance between the maxima increases, the number of maxima on the screen remains the same

the distance between the maxima remains the same, the number of maxima on the screen decreases

c) Diffraction experiments are usually done with diffraction gratings (which have many slits) instead of a double slit. The advantage of the diffraction grating over a double slit (using the same screen distance and slit width) is

there are many more maxima generated

it eliminates the central maximum    

all the maxima are farther apart

all the maxima are closer together

all the maxima are brighter

less light goes to the central maximum, and more to the other maxima

d) For this question, there is more than one correct answer. To get this question right, you must select all the correct answers!
You can change L (the distance from the slits to the screen), d (the distance between the slits) and λ (the wavelength of the light used). Which combination would double the distance between the maxima?

double L, leave λ and d unchanged

halve d, leave L and λ unchanged

halve L, halve d, halve λ

halve L, leave d and λ unchanged

double L, double λ, leave d unchanged

double λ, leave L and d unchanged

double d, halve L, leave λ unchanged

halve d, double λ, double L

double L, double λ, double d

halve d, double λ, leave L unchanged

double L, double d, leave λ unchanged

double L, halve d, leave λ unchanged

e) Suppose you are doing a double slit diffraction experiment with monochromatic (single frequency) light. Suddenly the atmosphere changes from air to a gas with a higher index of refraction. What will happen to the pattern?

the distance between the maxima will increase, the color of the light will change to a lower frequency

the distance between the maxima will decrease, the color of the light will remain the same    

the distance between the maxima will remain the same, the color of the light will change to a higher frequency

the distance between the maxima will increase, the color of the light will change to a higher frequency

the distance between the maxima will increase, the color of the light will remain the same

the distance between the maxima will remain the same, the color of the light will change to a lower frequency

the distance between the maxima will decrease, the color of the light will change to a lower frequency

the distance between the maxima will remain the same, the color of the light will remain the same

the distance between the maxima will decrease, the color of the light will change to a higher frequency