Mechanics | Relativity Answers

A 5 kg box is tossed across the floor at 4 m/s and slides to a stop in 3 s. What is the average force of friction?

A 70 kg person is at the top of a 10 m tall slide. Ignoring friction, what is his or her speed at the halfway point where he or she is 5 m from the bottom of the slide? What is his or her speed at the bottom of the slide?

An inclined plane is used to raise a 100 kg box to a height of 5 m. How long must the inclined plane be if a force of 250 N is used to push the box up the inclined plane?

. A 70 kg person is riding on a frictionless skateboard at 5 m/s. A friend facing him throws a 5 kg ball toward him at 20 m/s. What is his final speed after catching the ball

a boatman sails his boat at an speed of 3 km per hour straight to cross a 0.5 km wide river at an angle of 30 degree with the direction of flow whose velocity is 2 km per hour.but the boatman to save his time, sails his boat for 5 minutes in this condition.after that he change the angle to 60 degree and also change the speed of the boat to 4 km per hour and quickly cross the river.how much time he needed to cross the river totally????

1.
The figure above shows part of a system consisting of a block at the top of an inclined plane that rests on a
table, which is located on Earth. The block and plane are at rest when the block is released. In trial 1 there is
no friction between the block and the plane or between the plane and the table. In trial 2 the plane is fixed to
the table so it cannot move, but there is still no friction between the block and the plane.
(a) Indicate whether the speed of the block relative to the table when the block reaches the bottom of the
plane is greater in trial 1 or trial 2. Justify your answer in a clear, coherent, paragraph-length
explanation.
(b) Assuming the body has mass M and the plane has mass 3M and angle 30o, find the ratio of the speeds of
the block at the base of the plane, just before entering the curved area of the plane, in the 2 cases ( trial
1 / trial 2).

A man standing on a scale in an elevator notices this at the scale he reads 30 newtons greater than his normal weight. Which type of movement of the elevator could cause this greater-than-normal reading?

The starting height for a frictionless coaster on earth is 25 m. It's mass with 2 passengers is 300 kg. calculate the maximum GPE

A man of 2kg is thrown in the direction east with 2m/s velocity what is it's momentum?

A pilot performs an evasive maneuver by diving vertically at 310 m/s. If he can withstand an acceleration of 9.0g's without blacking out, at what altitude must he begin to pull out of the dive to avoid crashing into the sea