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p2something.png An object side a distance d down and incline of height ∆y as shown.  If the coefficient of friction between the surface and the object is 0.250, determine the work done by friction. m = 5.00 kg, d = 9.00 m,  and ∆y = 3.00 m.

A worker pushes a 8.0 kg crate across a level surface with a force of 35.0 N directed at an angle of 25.0° downward from the horizontal. Determine the work done by gravity after the crate is pushed 12.0 m.

A car of mass 1750 kg accelerates from 0.00 m/s to 35.0 m/s.  What was the net work done on the car? 

p2something.png An object slides a distance d = 9.00 m down an incline of height ∆y = 3.00 m as shown.  Determine the speed of the object at the bottom of the incline if it starts from rest and the coefficient of kinetic friction between the object and the surface is 0.25.

The force on an electric charge in an electric field is F = qE where F is the force, q is the electric charge, and E is the electric field.  Determine the speed of a proton (charge = 1.6×10-19 C, mass = 1.67×10-27 kg) after it has been accelerated, from rest, a distance of 0.25 m though an electric field of 2.0×106 N/C. 

A spring of spring constant 800 N/m is used to launch a 15.0 g projectile vertically upward.  By how much must the spring be compressed in order for the projectile to reach a maximum height of 35.0 m?

A child sleds down a 3.5 m tall snowy hill.  Ignoring friction, determine the child’s speed at the bottom of the hill.

A 500 kg ore cart traveling at 12.0 m/s on a level track is stopped by a spring of spring constant 35,000 N/m mounted horizontally at the end of the track.  By how much does the spring compress in stopping the car?

psoccer.png A 425 g soccer ball traveling horizontally along the ground at 15.0 m/s is kicked in the opposite direction by a player with a speed of 25.0 m/s at an angle of 60.00 up from the horizontal.  If the time of contact between the player and the ball for the kick was 0.025 s, what was the magnitude of the force exerted on the ball?

A 90.0 kg wide receiver traveling east at 15.0 m/s is tackled by a 115 kg linebacker traveling at 8.0 m/s in a direction of 300 west of north.  What are the speeds of the players (assume they stick together) just after the tackle?