A person pushes a 24.2-kg shopping cart at a constant velocity for a distance of 17.6 m on a flat horizontal surface. She pushes in a direction 22.7 ° below the horizontal. A 42.4-N frictional force opposes the motion of the cart. (a) What is the magnitude of the force that the shopper exerts? Determine the work done by (b) the pushing force, (c) the frictional force, and (d) the gravitational force.

An object is placed 27.2 cm to the left of a diverging lens (f = -10.6 cm). A concave mirror (f = 17.1 cm) is placed 40.3 cm to the right of the lens to form an image of the first image formed by the lens. Find the final image distance, measured relative to the mirror. (b) Is the final image real or virtual? (c) Is the final image upright or inverted with respect to the original object?

A tennis ball is thrown against a wall and rebounced. M(mass of wall)*v (for ball) =2*m(mass of ball) * V(for wall), KE(wall)=1/2 * Mv²; KE(in)=1/2 *mV² and

KE(out)=1/2 *mV²+1/2*Mv² ; If KE(in)=KE(out), Where did 1/2*Mv² go? Is the KE conderved? Prove it.

A 0.167-kg frame, when suspended from a coil spring, stretches the spring 0.0400 m. A 0.200-kg lump of putty is dropped from rest onto the frame from a height of 30.0 cm.

Find the maximum distance the frame moves downward from its initial equilibrium position.

The U.S. Navy conducts sonar tests that may be harmful to undersea creatures like whales and dolphins. Discuss the propagation of sound waves under water, and speculate on how Navy sonar waves might interfere with cetacean undersea navigation.

A student makes a short electromagnet by winding 540 turns of wire around a wooden cylinder of diameter d = 3.2 cm. The coil is connected to a battery producing a current of 4.3 A in the wire. (a) What is the magnitude of the magnetic dipole moment of this device? (b) At what axial distance z >> d will the magnetic field have the magnitude 5.0 µT (approximately one-tenth that of Earth's magnetic field)?

1# What is the conservation of momentum? Under what conditions is it true?

During the upcoming lab you will work as a class to test predictions as to when momentum is and is not conserved when you collide two gliders. You will have available gliders with different masses and different things you can mount on the end of gliders to interact (including springs, Velcro, magnets). Please identify at least a four different scenarios you could test that span a range of different conditions, including at least one in which you expect total momentum to be conserved and at least one in which you DO NOT expect total momentum to be conserved

2# in the upcoming lab, it will be useful to program Lab Assistant to make graphs of the momentum of each glider and the entire system. In the space below, please make a list of the

·         sensors you will need to set up,

·         derived waveforms and constants you will need to define, and

·         the formulas you will need to enter (including the actual equations)

3#Look over the example lab reports, particularly the abstract. What is the purpose of an abstract? What information is included in it? What information is not included in it? How does it differ from the introduction section?

Based upon the equation for potential energy, how does the potential energy change when the gravity is lower than it is on Earth

Example... gravity on the moon is 1.6 m/s2

Describe any differences you see in potential and kinetic energy between the Earth and Jupiter.

Describe any differences you see in potential and kinetic energy between the Earth and the moon.

Astronomers can measure the temperature of a star by comparing its brightness in blue and yellow light. Does reddening by interstellar dust affect a star's temperature measurement, and if so, how?

A 25-gram block is resting on a horizontal, frictionless surface and is attached to a horizontal spring of k = 210 N/m. The spring is stretched so that the block is 27 cm away from the spring’s equilibrium position and released from rest.

a) What is the velocity of the block when it passes through the equilibrium point?

b) At what distance from equilibrium is the spring’s potential energy equal to the block’s kinetic energy?

c) Suppose the block has a speed of 21 m/s when it passes through the equilibrium point for the first time, how much work is done by the force of kinetic friction during that first part of the block’s motion?

Group Work 3 – GI Joe (option 2)

G. I. Joe paratrooper Ripcord (80 kg) is invading Cobra HQ. He’s brought in by a stealth bomber, where he jumps from an altitude of 10,000 ft (approx 3000 meters).

What is his initial acceleration?

If the chute failed, what would his average acceleration be over the trip? Assuming the average acceleration, how fast would he hit the ground?

Derive an equation for the ratio of terminal velocities between diving head first vs. spread eagle (lying flat).

At 1,000 ft, he pulls the parachute cord (a 1m x 5m rectangular chute). What is his initial acceleration due to drag?

How long does it take to reach the ground at Cobra HQ if the parachute opens at 1,000 ft?

Young softball batters are often instructed to “choke-up on the bat” by their coach. In terms of the moment of inertia, what exactly does this accomplish and why is it an advantage to the young batter? Come up with one other real-life example where either increasing or decreasing the moment of inertia becomes an advantage? Clearly describe the example and talk about the variables involved.

A person standing on the edge of a high cliff
throws a rock straight up with an initial
velocity of 17.50 m/s. The rock misses the edge
of the cliff as it falls back to Earth. What is the
position and velocity of the rock at 1.00 s, 3.5 s
and 4.0 s after it is thrown, neglecting the
effects of air resistance.

1.       Prepare an explanation of the nonconserved work of pulling and friction forces. Observe what happens when you rub your hands together quickly. Also, observe what happens when you hold a heavy book out to your side for as long as you can. What form do you think the friction and muscle work would take?