motion

A rock is dropped off the side of a bridge and hits the water below 2 seconds later. What was the rock's velocity when it hit the water? What was the rock's average velocity as it fell?

Newton's laws

The mass of a certain elephant is 1,130kg. What is the elephant's weight in Newton's? Please show the work.

Newton's laws

In an experiment performed in a space station, a force of 60 Newtons causes an object to have an acceleration equal to 4 meters/sec squared. What is the objects mass?

Newton's laws

The mass of a fist during a particular karate blow is measured to be about 3,500m/s squared. If the mass of the fist was approximately 0.7kg, what was the maximum force?

Newton's laws

As a baseball is being caught, its speed goes from 30 to 0 m/s in about 0.005 seconds. Its mass is 0.145kg. What is the baseball's acceleration in m/s squared and in grams? What is the size of the force acting on it?

Newton's laws

On a highway curve with radium 50m, the maximum centripedal force that can act on a 1,000kg car going around the curve is 8,000 Newtons. What speed limit should be posted for the curve so that cars can negotiate it safely?

Energy and Conservation Laws

Which has the larger linear momentum: A 2,000-kg houseboat going 5 m/s or a 600-kg speedboat going 20 m/s?

Energy and Conservation Laws

A 3,000-kg truck runs into the rear of a 1,000-kg car that was stationary. The truck and car are locked together after the collision and move with speed 9 m/s. What was the original speed of the truck before the collision?

Energy and Conservation Laws

A rock weighs 100 lbs and is lifted 1 ft by a lever. How much work is done?

Energy and Conservation Laws

While in orbit about the earth, a space shuttle's mass is 80,000-kg and its speed is 7,900 m/s. What is its kinetic energy?