ENERGY AND MOMENTUM: A Windy Day at the Lake

Q: Wind blows a 43.0 kg raft across a lake at 1.1 m/s northward relative to the water underneath. It carries a passenger whose mass is 38.0 kg. The passenger begins to walk westward at 0.71 m/s. What is the final velocity of the raft relative to the water? A: We first determine the momentumContinue reading “ENERGY AND MOMENTUM: A Windy Day at the Lake”

ENERGY AND MOMENTUM: What is the final velocity of the hovering disk?

Q: A disk of mass 0.5 kg slides with a constant velocity of 2.4 m/s over an air table before colliding with an elastic band. If the band exerts an average force of 1.4 Newtons on the disk for 1.5 seconds, what is the final velocity of the disc? A1: The disc will experience aContinue reading “ENERGY AND MOMENTUM: What is the final velocity of the hovering disk?”

ENERGY and MOMENTUM: How Fast Will the Block Move When a Compressed Spring is Released?

Q: A spring with a spring constant k = 100 N/m is compressed a distance ( x ) = 100 mm. A block with a mass ( m ) = 0.250 kg is placed next to the spring. The surface upon which the block rests is frictionless and horizontal. When the spring and block areContinue reading “ENERGY and MOMENTUM: How Fast Will the Block Move When a Compressed Spring is Released?”

ENERGY and MOMENTUM: What is the Final Velocity of the Ball?

Q: A 10 kg iron ball moves in an Eastward direction at 5.0 m/s. It collides with a 5.0 kg rubber ball moving Northward at 10 m/s. After the collision, the iron ball moves 60° East of North with a speed of 4.0 m/s. What is the velocity of the rubber ball after the collision?Continue reading “ENERGY and MOMENTUM: What is the Final Velocity of the Ball?”

ENERGY AND MOMENTUM: Subatomic Collisions, Billiard Balls, and the 90-Degree Rule ( Part 1 )

An elastic collision, within which kinetic energy ( KE ) and momentum ( p ) are conserved, is mathematically modeled in terms of momentum as follows:  pi = pf , and m1v1i + m2v2i = m1v1f + m2v2f  where p = mv, and m = mass in kilograms ( kg ), and velocity ( vContinue reading “ENERGY AND MOMENTUM: Subatomic Collisions, Billiard Balls, and the 90-Degree Rule ( Part 1 )”

ELASTIC COLLISIONS: Kinetic Energy, Momentum, Two Equations, and Two Unknown Variables

If a + b = c, and if b = e + f, then it’s also true that a + e + f = c. Any time a variable is common to two or more similar equations, solving one of the two equations will enable us to substitute the common variable into the remaining equation.Continue reading “ELASTIC COLLISIONS: Kinetic Energy, Momentum, Two Equations, and Two Unknown Variables”