A 56-kg roller coaster is moving at 39 m/s at point (2) in the figure. What was its kinetic energy at point (1)? Assume no work is done by non-conservative forces. Answer in Joules

An object is displaced by 0.5m against a force of friction at 2N. What is the work done on the object by the friction? -6J 1J -1J 4J

Assume that a common flea can jump straight up to a maximum height of 20 cm. If the flea has mass m = 0.5 milligrams, calculate the potential energy of the flea (in Joules, J) once it reaches its maximum height.  If the flea in jumps to its maximum height but misses jumping onto a 4-legged friend, then obviously, the flea will fall to the ground. Calculate the force of gravity acting on the flea, during its free-fall to the ground? Assume that the flea falls straight down from its maximum jump height. Express the answer in Newtons.

How much work can a 1950 Watt motor do in 15 min? Express your answer in Joules.

a weight lifter holds a 50kg weight a distance of 3m above the ground for 30 seconds.How much work is done on the weight in that time? Calculate it both ways and make sure that they match.

3) The figure below illustrates a skier who is skiing on a large frictionless spherical ball of snow. The skier can be treated as a point-like object. The skier starts at the top of the ball with very little speed and picks up speed while traveling along the surface of the snow. During this time, the only forces acting on the skier are the gravitational force applied by the Earth and the normal force applied by the snow. At the moment the radial line extending from the skier to the center of the ball defines an angle a with respect to a vertical line, the skier is about to lose contact with the ball. Determine the value of a.

Estimate the work (in J) you do to mow a lawn 20m by 20m with a 60-cm-wide mower. Assume you push with a force of about 25 N.Final answer in 2 decimal places.

How much work (in Joules) is done by a 32N force acting over a distance of 8m?  Assume the force is in the same direction as the displacement.

Tom used 100N of force to drag a 10kgs of rocks up a 15 degree hill. There is an initial velocity of 1.5 m/s. The coefficient of kinetic friction is 0.40 and the rocks is dragged 7.5m. Find the work done in gravity? The work done by friction? The work done by Tom? The change in KE? The speed of the rocks after it is dragged 7.5m?

A conservative force of 22.5 N moves a particle of 1 gram along a circular path, oriented vertically, of diameter 50 cm. What is the work done by the conservative force, in Joules, in one cycle? Assume g = 10 ms ². Round to one decimal.