An ancient wooden club is found that contains74g of carbon and has an activity of 7.7 decays per second.

Determine its age assuming that in living trees the ratio of 14C/12Catoms is about 1.3

A soccer player kicks a lock horizontally of a 46 m high cliff into a pool of water. If the player hears the sound of the splash 3.26 s later, (a)what was the initial speed given to the rock in m/s?assume a speed of sound in air is 343 m/s. (b)What if the temperature near the cliff suddenly falls to 0ﾟ C reducing the speed of sound of 331 m/s, what would the initial speed of the rock have to be in m/s for the soccer player to hear the sound of the splash 3.26 s after kicking the rock?

6. In each situation described below, compare the magnitudes of the two forces. Explain your answer in each case.

g. A truck attempts to tow a car. They are connected by a 2-m-long rope. At first the truck doesn’t pull hard enough, and the car doesn’t move. Compare the force exerted by the truck’s bumper on the rope to that exerted by the rope on the truck’s bumper. Also compare the force exerted by the rope on the car’s bumper to that exerted by the car’s bumper on the rope.

h. Finally the truck pulls hard enough so that the car begins to move. Compare the same pairs of forces as in (g) to each other.

i. An elevator is hanging from a strong cable. The elevator is at rest. Compare the force exerted by the cable on the elevator to that exerted by the elevator on the cable.

j. In (i) compare the tension in the cable to the weight of the elevator.

k. The elevator in (i) begins accelerating upward. Now compare the force exerted by the cable on the elevator to that exerted by the elevator on the cable.

l. In (k) compare the tension in the cable to the weight of the elevator.

m. The elevator in (i) is moving upward at a constant velocity. Now compare the force exerted by the cable on the elevator to that exerted by the elevator on the cable.

n. In (m) compare then tension in the cable to the weight of the elevator.

The potential difference from the cathode (negative electrode) to the screen of an old television set is +22,000 V. An electron leaves the cathode with an initial speed of zero.

a)Determine the kinetic energy of the electron.

b)Determine the speed of the electron.

Chuck and Jackie stand on separate carts, both of which can slide without friction. The combined mass of Chuck and his cart, mcart, is identical to the combined mass of Jackie and her cart. Initially, Chuck and Jackie and their carts are at rest. Chuck then picks up a ball of mass mball and throws it to Jackie, who catches it. Assume that the ball travels in a straight line parallel to the ground (ignore the effect of gravity). After Chuck throws the ball, his speed relative to the ground is vc. The speed of the thrown ball relative to the ground is vb. Jackie catches the ball when it reaches her, and she and her cart begin to move. Jackie's speed relative to the ground after she catches the ball is vj. When answering the questions in this problem, keep the following in mind: The original mass mcart of Chuck and his cart does not include the mass of the ball. The speed of an object is the magnitude of its velocity. An object's speed will always be a nonnegative quantity.

Discuss the discoveries that LIGO has made. Why are these discoveries considered to be direct detection of gravitational waves?

A smooth circular hoop with a radius of 0.600 m is placed flat on the floor. A 0.450-kg particle slides around the inside edge of the hoop. The particle is given an initial speed of 9.50 m/s. After one revolution, its speed has dropped to 4.50 m/s because of friction with the floor.

(a) Find the energy transformed from mechanical to internal in the particle—hoop—floor system as a result of friction in one revolution.

_____J

(b) What is the total number of revolutions the particle makes before stopping? Assume the friction force remains constant during the entire motion.

_____rev

An attacker at the base of a castle wall 3.75 m high throws a rock straight up with speed 8.50 m/s from a height of 1.50 m above the ground.

(a) Will the rock reach the top of the wall?

(b) If so, what is its speed at the top? If not, what initial speed must it have to reach the top?

(c) Find the change in speed of a rock thrown straight down from the top of the wall at an initial speed of 8.50 m/s and moving between the same two points.

(d) Does the change in speed of the downward-moving rock agree with the magnitude of the speed change of the rock moving upward between the same elevations?

(e) Explain physically why it does or does not agree.

I tried to ask this question before, but got the wrong answer. I know for a, the answer is yes. I can't figure out the rest. Thanks!

1. Why is the conductivity of metal different from the insulator? - How different is the semiconductor from them?

2. What is the main cause of the energy gap? How is it related to the Bragg condition.

3. How is Bloch function different from the general wavefunction?

What do you think a dream yard for kids? What would they like to do there? What kinds of things should this yard have? Why? Explain your thoughts.

what are some pros of using solar energy over fossil fuels?

A 5.34g bullet leaves the muzzle of a rifle with a speed of 348 m/s. What force (assumed constant) is exerted on the bullet while it is traveling down the 0.812 m long barrel of the rifle?

The concepts in this problem are similar to those in Multiple-Concept Example 4, except that the force doing the work in this problem is the tension in the cable. A rescue helicopter lifts a 76.8-kg person straight up by means of a cable. The person has an upward acceleration of 0.500 m/s² and is lifted from rest through a distance of 8.64 m. (a) What is the tension in the cable? How much work is done by (b) the tension in the cable and (c) the person's weight? (d) Use the work-energy theorem and find the final speed of the person.

In this Topic, you have learned the terms used to describe motion (e.g., distance, speed, and acceleration) as well as Newton's laws explaining motion. Describe at least two ways the material you have learned in this unit applies to driving a car (refer to the Arizona Driver License Manual located within the weekly readings). Has what you have learned in this Topic changed how you drive? If so, please explain.

The figure shows 3 point charges at the corners of a rectangle. The top left corner is positive 10nC and the bottom left corner is 5 nC they are both positive. The top side is 3cm while the right side is 4cm the bottom and the left sides are also the same. The top right corner is -10 nC. A -15nC charge is placed at the emply corner that being the bottom right.

A) find the electric potential at the center of the rectangle

B) find the electric potential energy of the configuration.