Chapter 6.1, Problem 6.1CC

Describe the gravitational potential energy transfers and transformations for a javelin, starting from the point at which an athlete picks up the javelin and ending when the javelin is stuck into the ground after being thrown.

It is common practice in driving to ease one's foot from the gas pedal when driving downhill. Which of the following statements is correct regarding the underlying physical principle that explains why this method of coasting is practical?   Question 7 options:   The kinetic energy of the car is converted to gravitational potential energy as the car moves down the hill.   The wheels are allowed to rotate freely while coasting so braking is more effective.   The wheels are allowed to rotate freely while coasting so less friction is encountered.   The gravitational potential energy of the car is converted into kinetic energy as the car moves down the hill.

A particle of mass m moves in the XY-plane, and its position vector is given by = a cos wtî + b sin wtĵ where a, b, and w are positive constants, and a > b. Show that a. The particle moves in an ellipse. b. The force acting on the particle is always directed toward the origin. c. The total work done by the force in moving the particle once around the ellipse is zero d. The force is conservative.