Action of Forces and Torques - The drawing shows a jet engine suspended beneath the wing of an airplane. The weight W of the engine is 9600 N and acts as shown in the drawing. In flight the engine produces a thrust T of 62400 N that is parallel to the ground. The rotational axis in the drawing is perpendicular to the plane of the paper. With respect to this axis, find the magnitude of the torque d...

Center of Gravity - A man holds a 178 N ball in his hand, with the forearm horizontal (see the drawing). He can support the ball in this position because of the flexor muscle force M, which is applied perpendicular to the forearm. The forearm weighs 20.2 N and has a center of gravity as indicated. (a) Find the magnitude of M. (b) Find the magnitude and direction of the force applied by the...

Rotational work and energy - (a) Calculate the kinetic energy that the earth has because of its rotation about its own axis. Assume that the earth is a uniform sphere and that its path around the sun is circular. For comparison, the total energy used in the United States in one year is about 9.33 109 J. (b) Calculate the kinetic energy that the earth has because of its motion around the sun.

Running on circular platform - Suppose a 60kg person stands at the edge of a 6.0m diameter circular platform, which is mounted on frictionless bearings and has a moment of inertia of 1800kgm^2. The platform and runner are initially at rest. Calculate the angular velocity of the platform if the runner begins to run 4.2m/s.

Finding a Spring Constant - Assuming negligible friction, what spring constant would be needed by the spring in a "b-b gun" to fire a 10g pellet to a height of 100m if the spring is initially compressed 10cm?