Physics Answers

15. A group of construction workers push against a large crate, trying to get it to move, but failing. Another coworker pushes a much smaller box and boasts he did more work. Is this true?

A. No, because he exerted less force.

B. No, because he moved an object with a smaller mass.

C. Yes, because he did the work alone.

D. Yes, because the small box moved, while the big box did not.

A mass of 10 kg, which may be a point-like object, is attached to a rope of length 1.5 m and is being rotated. What is the moment of inertia(in kg. meter squared) of the object?

Three different gases, namely; He, N2 and CO2 were placed in separate containers.

16. Which of the following is the closest value of Cv for the He gas?

Lesson: Torque

Instruction: Analyze and solve the following problems step-by-step.

1. Find the total torque acting on a body when three forces are applied on the following: F1=10 N upward at 1 m,F2=20n upward at 2 m and F3=5N downward at 0.5 m.

Show that the expression for the electric field of a charged disk showing in the equation below reduces to that of a point for Z>>R, where all symbols have their usual meanings.

σ/2εo[ 1= z/√z^2+R^2]

Angular Momentum

Solve the problems.

1. A small particle of mass 0.20 kg is being whirled in a horizontal circle at the end of a 20 m long string at a constant speed of 1.0 m/s. Determine ito angular momentum about its axis of rotation.

2. A bowling ball has a mans of 5.5 kg and a radius of 12.0 cm. It is released so that it rolls down the alley at a rate of 12 rev/s. Find the magnitude of its angular momentum

Moment of Inertia

Analyze and solve the given problem.

A system consists ( thin-hollowed sphere) of three email masses rotating at the same speed about the same fixed axis The masses and their radii of ratation are: 16 g at 256mm, 23 g at 192 mm and 31 g at 176 mm. Determine (a) the moment of inertia of the system about the given axis.

The nucleus of an atom of uranium - 238 has a radius of 6.8×10^-15m and carries a positive charge of Ze in which Z(=92) is the atomic number of uranium and e is the elementary charge, (1) What is the electric field at the surface of such a nucleus?, (2) In what direction does it point?, (3) Does it's numerical value surprise you?, (4) Explain your answer.

A particule leaves the origin with a speed of 3×10^6m/s at 35° to the x-axis, it moves in a constant electric field E=E,j. Find Ey such that the particle will cross the x-axis at x=15cm if the particle is (a) an electron (b) a proton

An electron moves in a circular orbit about a stationary proton, the centripetal force is provided by the electrostatic force of attraction between the proton and the electron, assuming that the electron has a kinetic energy of 3×10-18J, what is the speed of the electron and the radius of the orbit of the electron.