How is momentum defined?

Momentum = force × time Momentum = mass × velocity Momentum = mass × acceleration Momentum = energy ÷ speed

A 3 kg ball moves at 4 m/s. What is its momentum?

7 kg·m/s 0.75 kg·m/s 12 kg·m/s 48 kg·m/s

Which has more momentum: a 0.5 kg tennis ball moving at 60 m/s, or a 3 kg bowling ball rolling at 5 m/s?

The bowling ball — it is heavier The tennis ball — 0.5 × 60 = 30 kg·m/s versus 3 × 5 = 15 kg·m/s They have equal momentum — both are 30 kg·m/s Neither — only moving objects of the same mass can be compared

What does the law of conservation of momentum state?

Momentum always increases in a collision Momentum is destroyed when objects stop moving In a closed system, the total momentum before any interaction equals the total momentum after Momentum is conserved only in elastic collisions

Two ice skaters stand still facing each other. They push off and skate apart. Before the push their total momentum was zero. What is the total momentum after the push?

Double their individual momenta — the push created new momentum Equal to the stronger skater's momentum Zero — their individual momenta are equal and opposite, so they cancel Impossible to determine without knowing their masses

What is an elastic collision?

A collision where the objects stretch like elastic before bouncing A collision where both momentum and kinetic energy are conserved A collision where only momentum is conserved, not kinetic energy A collision between objects made of rubber

Two clay balls collide and stick together. What type of collision is this?

Elastic — because the collision is between soft objects Perfectly inelastic — the objects merge, and kinetic energy is lost (though momentum is still conserved) Neither — momentum is not conserved when objects stick together Inelastic — kinetic energy increases because the objects combine

A 1 kg ball rolling at 6 m/s hits a stationary 2 kg ball and they stick together. What is their combined speed after the collision?

6 m/s 3 m/s 2 m/s 4 m/s

Why are car bumpers and crumple zones designed to deform in a crash?

They absorb momentum so the passengers don't have to They make the car lighter, which reduces momentum before the crash Increasing the time of the collision reduces the force on the passengers, even though momentum change stays the same Deformation converts all kinetic energy to momentum, making the crash safer

A stationary cannon fires a cannonball forward. The cannon rolls backward. What principle explains this?

Newton's Third Law only — the cannon pushes the ball and the ball pushes back The explosion pushes everything backward, including the cannon Conservation of momentum — the total momentum was zero, so ball and cannon must have equal and opposite momenta after firing Conservation of energy — the kinetic energy splits equally between ball and cannon