An elevator has a mass of 2,000 kg.  An upward force of 21,000 Newtons is applied to the elevator. The elevator travels up 50 floors, and each floor is 2.5 meters tall, with a 20 centimeter gap between floors. How long does it take the elevator to arrive, and at what speed will it be traveling?

If the coefficient of kinetic friction between a 35 kg crate and the floor is .30, what horizontal force is required to move the crate at a steady speed across the floor? What horizontal force is required if µ_k is zero?

A 5.0 kg missle is projected from rest to a speed of 4.5 x 10³ m/s. How much time is required to do this by a net force of 5.3 x 10⁵ N?

A mass, m₁, accelerates at 3 m/s² when a force, F, is applied. A second mass, m₂, accelerates at 1.0 m/s² when F is applied to it.

1. Find the value of the ratio m₁/m₂.
2. Find the acceleration of the combined mass ( m₁ + m₂) under the action of the force, F.
    

A hockey stick travels backward 11.0 cm while intercepting a 0.140 kg puck. How much force did the stick exert on the puck to bring the puck from 35.0 m/s to rest?

A 50 kg sled starts at rest, and is being pushed across a horizontal frictionless surface with a force of 30 N. The wind is pushing against the sled. The sled travels 100 meters while accelerating to 10 m/s. What is the force of the wind on the sled?

Howard is standing in the middle of a skating rink (we'll assume no friction), and his four friends Alice, Bernie, Christopher, and David approach him from each of the four compass directions - north, east, south, and west, respectively.

Alice pushes on Howard with a force of x + 20 Newtons. Bernie pushes on him with a force of 2x + y Newtons. Christopher pushes on him with a force of 2x - y Newtons, and David pushes with a force of 5y Newtons.

Howard, though being pushed from all directions, does not move. Calculate the forces being applied in all four directions.

A 1000-kg car moving north at 100km/h brakes to a stop in 50m. What are the magnitude and direction of the force?

 

A force is applied to a 1000 kg car, and causes the car to accelerate from 0 m/s to 25 m/s while traveling 200 m. The same force is applied to a 600kg motorcycle.  How far will the motorcycle travel while accelerating from 10 m/s to 40 m/s?

A 50 slug car can accelerate from 0 to 50 ft/s while traveling 1000 feet. The car then stops, and a passenger gets in. Now the car can accelerate from 0 to 50 ft/s while traveling 1050 feet. What is the weight of the passenger?