a) How did interstellar extinction mislead astronomers into believing that we are at the center of our galaxy?

b) Describe how Harlow Shapley proved that the Sun is not at the center of our galaxy.

Imagine you are a punter on a football team and the coach tells you to give your players a chance to get down the field. With which angle with the horizontal would you punt the ball? Explain. A. 15 degrees B. 45 degrees C. 65 degrees D. It doesn't matter.

When you hold an insect at the near point of your eye it subtends an angle of 5.00 10-3 rad. Determine the maximum angular size of the insect when viewed through a magnifying glass (simple magnifier) that has a focal length of 8.70 cm.

explain how the process of doping is attained to achieve extrinsic semiconductors with different electrical properties ?

describe how the energy gap of a semiconductor is different from that of insulator and conductor .

Suppose a charge of -2.40 µC is at the origin and a charge of 3.10 µC is at the point (0, 3.00) m.

(a) Find the electric potential at (4.00, 0) m, assuming the electric potential is zero at infinity. What is electric potential? What factors affect the size of the electric potential at a particular point?

(b) Find the work necessary to bring a 4.10 µC charge from infinity to the point (4.00, 0) m.

A stone is dropped at t = 0. A second stone, with twice the mass of the first, is dropped from the same point at t = 234 ms.
How far below the release point is the center of mass of the two stones at t = 326 ms? (Neither stone has yet reached the ground.)

How fast is the center of mass of the two-stone system moving at that time?

Briefly describe how the distance traveled by the football might be different if the landing height was different than the release (kicking) height?

A)

A student stretches an elastic band by 0.8 m in 0.5 seconds. The spring constant of the elastic band is 40 N/m. What was the power exerted by the student?

B)

A student pushes a 0.2 kg box against a spring causing the spring to compress 0.15 m. When the spring is released, it will launch the box vertically into the air. What is the maximum height the box will reach if the spring constant is 300 N/m?

C)

A student connects a 1 hp motor to a bicycle. How much time will it take for the bicycle to accelerate from rest to a speed of 5.0 m/s if the combined mass of the student and the bicycle is 120 kg? (1 hp = 746 W)

A youngster is holding a ball with a diameter of 5.60 cm and average density of 0.0837 g/cm³ under water. Determine the force (in N) needed to hold it completely submerged.

magnitude  N

direction ---Select--- upward downward

Two point charges, q₁= +2 nC and q₂= -18 nC, are located on the x-axis at x= 0 and x=4 m. What is the distance of ZERO electric field from the positive charge?

why is a car a good place to hide from lightning? [try to explain in terms of electric fields]

Discuss the magnet, gradient coils, and RF coils in a MRI scanner. Include a figure and some of the design considerations required for each component.

Amy and bob are in an archery competition. the goal is to hit a target taht is on a wall 50m away from them horizontally. the target is 21m vertically above the ground, and both competitors hold their bows 1m above the ground, so the vertical displacement is 20m. they both use the same bow, which shoots arrows at a speed of 35 m/s at the moment of release.

A) Bob decides to aim directly at the target. what angle has bob chosen?

B) Bob shoots and misses. He forgot to account for the effect of gravity when he aimed; he failed to aim above the target, so his arrow ends up below the target. Exactly how far below the target does Bob's arrow hit the wall?

C)Amy knows what she must aim above the target to make the shot. In fact, there are actually two angles that will cause her to hit the target. What are they?

D)Roughly sketch the path for all three arrows: Bob's miss and Amy's two possible hits.

A baseball player at bat hits a ball to the outfield. The baseball is hit when it is at a height of 1.60 m above the home plate. The ball’s velocity the instant it is hit is 34.00 m/s at an angle of exactly 54.00^o above the horizontal. The ball lands safely in the outfield. Assume that the entire baseball ground is horizontal.

(a) What are the vertical and horizontal components of the ball’s acceleration while it is in the air?

(b) What are the vertical and horizontal components of the baseball’s speed the instant after it was hit?

(c ) What is the maximum height of the baseball above the ground?

(d) What is the Range of the baseball?

(e) What is the velocity (vector) of the ball the instant before it hits the ground?