gravity

a mass of 100kg weighs 980.6N at sea level. estimate the weight of this body at the top of a mountain 5km high. assume that the mean diameter of the earth is 12742km

Microscopic Interpretation of Entropy

A box is seperated by a partition into two parts of equal volume. The left side of the box contains 500 molecules of nitrogen gas; the right side contains 100 molecules of oxygen gas. The two gases are at the same temperature. The partition is punctured, and equilibrium is eventually attained. Assume that the volume of the b ...continues

Equilibrium of a Rigid Body

One end of a post weighing 500N and with height h rests on a rough horizontal surface coefficient of static friction equal to .40. The upper end is held by a rope fastened to the surface and making an angle of 37 degrees with the post (see attached figure). A horizontal force F is exerted on the post as show in the attached di ...continues

Collisions

1. During a violent thunderstorm, hail of diameter 1.0 cm falls directly downward at speed of 25m/s. There are estimated to be 120 hailstones per cubic meter of air. (a) what is the mass of each hailstone ( density = 0.92 g/cm^3) ? (b) Assuming that the hail does not bounce fine the magnitude of the average force on a flat roof ...continues

Rotation

1. A wheel has 8 equally spaced spokes and a radius of 30 cm. It is mounted on a fixed axle and is spinning at 2.5 rev/s ( revolutions per second ). You want to shoot a 20 cm long arrow parallel to this axle and thought the wheel without hitting any of the spokes. Assume that the arrow and the spokes are very thin. (a) What mini ...continues

rotation

1. At t=0, a fly wheel has an angular velocity of 4.7 rad/s (radians per second), an angular acceleration of -0.25 rad/s^2 , and a reference line at pheta0 = 0. (a) Through what maximum angle phetamax will the reference line turn in the positive direction ? At what times t will the reference line be at (b) pheta = 1/2phetamax an ...continues

Spacecraft orbiting -- need to find the period

A spacecraft is in orbit around Jupiter. The radius of the orbit is 3.0 times the radius of Jupiter (RJupiter = 71,500 km). The gravitational acceleration at the surface of Jupiter (the surface is defined as the above radius) is 23 m/s2. Without using any other information about Jupiter, what is the period of the spacecraft's ...continues

Block Sliding down a frictionless plane at an angle

A 4.0 kg block is released from rest at the top of a frictionless plane of length 8.0 m that is inclined at an angle of 15° to the horizontal. A cord is attached to the block and trails along behind (assume the cord is massless). When the block reaches a point 5.0 m along the incline from the top, someone grasps the cord and ...continues

Rotation problems

1. At t=0, a fly wheel has an angular velocity of 4.7 rad/s (radians per second), an angular acceleration of -0.25 rad/s^2 , and a reference line at pheta0 = 0. (a) Through what maximum angle phetamax will the reference line turn in the positive direction ? At what times t will the reference line be at (b) pheta = 1/2phetamax an ...continues

Find Kinetic energy of earth due to its rotation about its axis.

Assume the Earth is a uniform solid sphere. Find the kinetic energy of the Earth due to its rotation about its axis. Suppose we could somehow extract 1.0% of the Earth's rotational kinetic energy to use for human needs. By how much would that change the length of the day? For how many years would 1.0% of the Earth's rotation ...continues