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work-1: A force of 120 N pushes a crate of mass 15 kg along the ground at a constant speed of 3.2 m/s for a distance of 6.2 m. What amount of heat energy was generated during this time? | work-2: A man pulls a cable that is attached to a heavy box with a force of 50.0 N. The cable makes an angle of 30o with the horizontal. If he pulls the box for a distance of 5 m, find the work done by the man. Find the work done by the man if he pulls the box with a horizontal force of 50.0 N. |
work-3 A woman rides a sled down a 10 m high frictionless slope. If she starts off with a speed of 6 m/s, what is her speed at the bottom of the hill? | work-4 A construction worker lifts a 30.0 kg wooden block tied to a rope from ground level to the roof and does 8.00 kJ of work. What is the height of the roof? Assume that the speed of the block remains the same. |
work-5 A student pulls a table with a force of 40 N directed at an angle of 20o downward from the horizontal. Find the work done by the student as she moves down a 100 m length of floor. | work-6 One end of a rope of length 12.0 m is fixed to a tree limb above. A monkey, whose mass is 8.0 kg, holds onto the free end of the rope and swings back and forth. Eventually, he gets the rope to swing enough that he can reach a branch when the rope makes a 60o angle with downward vertical. How much work is done against the force of gravity? |
work-7 A 80 kg baseball player slides into second base when moving at a speed of 5.0 m/s. The coefficient of friction between him and the ground is 0.73. His speed as he reaches the second base is zero. (a) How much mechanical energy is lost due to friction? (b) How far does he slide? | work-8 A 50.0 kg wooden box was pushed with a horizontal force of 140 N for a distance of 6.00 m on a rough horizontal surface. If the box moves at a constant speed, find (a) the work done by the force and (b) the coefficient of kinetic friction. |
work-9 A traveler pulls his 60.0 N carry-on bag a distance of 250 m along an airport floor at a constant speed with a force of 50.0 N directed at an angle of 55o above the horizontal. Find (a) the work he does, (b) the force of friction, and (c) the coefficient of kinetic friction between the bag and the floor. | work-10 A boy throws a 140 g ball at a speed of 45 m/s and an initial angle of 30.0o.What is the kinetic energy of the ball at the highest point of its path? |
work-11 A 6.0 g bullet moving at 500 m/s penetrates a sturdy wooden block to a depth of 3.00 cm. (a) Use work and energy considerations to find the average frictional force that stops the bullet. (b) Determine the time between the moment the bullet enters the block and the moment it stops moving. | work-12 A 0.70 kg object has a speed of 3.0 m/s at point P and kinetic energy of 8.0 J at point Q. What is (a) its kinetic energy at P? (b) its speed at point Q? (c) the total work done on the object as it moves from point P to Q? |
work-13 A 2.3 g bullet leaves the barrel of a gun at a speed of 350 m/s. Find (a) its kinetic energy as it leaves the barrel. (b) the average force exerted on the bullet during its travel through the barrel. Assume that the length of the barrel is 55 cm. | work-14 A 15 kg crate is pulled up a rough incline with a force of 150 N applied parallel to the incline, which makes an angle of 30o with the horizontal. Initial speed of the crate is 2.0 m/s. If the coefficient of kinetic friction is 0.47 and the crate is pulled a distance of 6.0 m, (a) how much work is done by the gravitational force? (b) How much work is done by the frictional force (c) what is the work done by the 150 N force and (d) What is the change in kinetic energy of the crate? |
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