A cord is used to vertically lower an initially stationary block of mass M = 8.5 kg at a constant downward acceleration of g/9. When the block has fallen a distance d = 4.9 m, find (a) the work done by the cord's force on the block, (b) the work done by the gravitational force on the block, (c) the kinetic energy of the block, and (d) the speed of the block. (Note : Take the downward direction positive)

A 67.5-kg skier coasts up a snow-covered hill that makes an angle of 25.7° with the horizontal. The initial speed of the skier is 8.68 m/s. After coasting a distance of 2.47 m up the slope, the speed of the skier is 3.79 m/s. (a) Find the work done by the kinetic frictional force that acts on the skis. (b) What is the magnitude of the kinetic frictional force?

A young woman on a skateboard is pulled by a rope attached to a bicycle. The velocity of the skateboarder is v⃗ → = (5.1 m/sm/s )x^ and the force exerted on her by the rope is F⃗ → = (17 NN)x^+ (12 NN)y^. Find the work done on the skateboarder by the rope in 20 seconds.

A 68.3-kg skier coasts up a snow-covered hill that makes an angle of 25.5 ° with the horizontal. The initial speed of the skier is 9.77 m/s. After coasting a distance of 1.45 m up the slope, the speed of the skier is 3.60 m/s. (a) Find the work done by the kinetic frictional force that acts on the skis. (b) What is the magnitude of the kinetic frictional force? (a) Number i (b) Number i Units Units 0

A 62.7-kg skier coasts up a snow-covered hill that makes an angle of 20.4 ° with the horizontal. The initial speed of the skier is 8.61 m/s. After coasting a distance of 2.21 m up the slope, the speed of the skier is 4.14 m/s. (a) Find the work done by the kinetic frictional force that acts on the skis. (b) What is the magnitude of the kinetic frictional force?

In the figure, a block of mass m = 1.40 kg slides head on into a spring of spring constant k = 220 N/m. When the block stops, it has compressed the spring by 14.0 cm. The coefficient of kinetic friction between block and floor is 0.280. While the block is in contact with the spring and being brought to rest, what are (a) the work done by the spring force and (b) the increase in thermal energy of the block-floor system? (c) What is the block's speed just as the block reaches the spring? (a) Number (b) Number i i (c) Number i Units Units Units 4 ←

A cord is used to vertically lower an initially stationary block of mass M = 2.5 kg at a constant downward acceleration of g/6. When the block has fallen a distance d = 3.8 m, find (a) the work done by the cord's force on the block, (b) the work done by the gravitational force on the block, (c) the kinetic energy of the block, and (d) the speed of the block. (Note : Take the downward direction positive)