Your task is to defend the Disney Castle from attackers. You have a catapult with which you can lob a rock with a launch speed of 14.2 m/s. from the courtyard over the walls onto the attackers at an elevation of 7.20 m. below that of the courtyard. What is the speed with which the rock will hit the ground at the attacker’s camp? Note: Use the Law of Conservation of Mechanical Energy.

A brick lies perilously close to the edge of the flat roof of a building. The roof edge is 50 ft above street level, and the brick has 260.0 J of potential energy with respect to street level. Someone edges the brick off the roof, and it begins to fall. What is the brick’s kinetic energy when it is 35 ft above street level? What is the brick’s kinetic energy the instant before it hits the street surface?

A daredevil on a motorcycle leaves the end of a ramp with a speed of 29.0 m/s as in the figure below. If his speed is 27.3 m/s when he reaches the peak of the path, what is the maximum height that he reaches? Ignore friction and air resistance.

. A skateboarder at a skate park rides along the path shown in figurebelow. If the speed of the skateboarder at point A is v = 1.64 m/s,what is her speed at point B? Assume that friction is negligible

A ball is thrown from 1.30 m above the ground with initial speed of 22.2 m/s at an angle of 42.7 ° above horizontal. (Assume no air resistance.) What is the ball's impact speed when it hits the ground? (a) Solve using kinematics. (b) Verify your answer by solving with work and energy concepts. Impact speed: m/s (c) At what angle does the ball hit the ground? Impact angle: degrees from horizontal You are not required to draw motion graphs or a Free-Body Diagram for this problem. However, you must clearly show all of the other problem-solving steps.

Shawn  (m = 48.5 kg)  rides his skateboard at a local skate park. He starts from rest at the top of the track as seen in the figure below and begins a descent down the track, always maintaining contact with the surface. The mass of the skateboard is negligible, as is friction except where noted. (a) What is Shawn's speed when he reaches the bottom of the initial dip, 12.0 m below the starting point? m/s(b) He then ascends the other side of the dip to the top of a hill, 8.0 m above the ground. What is his speed when he reaches this point? m/s(c) As he begins to descend again, down a straight, 18.0-m-long slope, he slows his skateboard down by using friction on the tail of the board. He is able to produce a friction force with a magnitude of 130.4 N. What is the change in thermal energy of the board-rider-track system as he descends the 18.0-m length of track? J(d) What is his speed when he reaches the bottom (the end of the 18.0-m length of track)? m/s

A box of mass 4.0 kg hangs by a cable from the ceiling of an elevator. The elevator is moving up at a steady speed of 5.0 m/s for 8.0 m. Use g = 10 m/s2. Consider the system is the box and the Earth. When apply the following energy principle, considering the system is box+earth, which of the energy term is positive? Select all apply. ΔK + ΔUg + ΔUsp + ΔEth + ΔEch = Wext Answer choice     ΔK     ΔUg      ΔUsp     ΔEth      ΔEch     Wext

In the figure here, a block of ice slides down a frictionless ramp at angle 0=51.0 the ramp. As the block slides down through distance d = 0.580 m along the ramp, its kinetic energy increases by 83.0 J. How much greater would its kinetic energy have been if the rope had not been attached to the block? while an ice worker pulls on the block (via a rope) with a force that has a magnitude of 51.0N and is directed up F, Number Unit