Ch 6 Momentum and Impulse Momentum Momentum the

Ch. 6 Momentum and Impulse

Momentum

Momentum – the product of an object’s mass and velocity § it is a vector quantity § The direction is the same as the velocity § The symbol is “p”

Formula momentum = mass x velocity p (kg • m/s) = m kg x v m/s

§ Impulse – the product of the force and the time over which it acts on an object Δp F= ------Δt

Impulse

§ The larger the mass, the greater the momentum compared to a less massive object with the same velocity. § If mass is constant, the larger the velocity the greater the momentum. § A change in momentum over a longer time requires less force

§ A change in momentum takes force and time. § The larger the momentum, the more force and/or time it will take to change the momentum

§ Force and time act together to change momentum.

§ Stopping times and distance depend on the impulse-momentum theorem Impulse = change in momentum §F Δ t = Δ p §F Δ t = p f - p i §FΔt = mvf - mvi

§ A large force over a short time will have the same effect as a small force over a long time.

A 2250 kg pickup truck has a velocity of 25 m/s to the east. What is the momentum of the truck?

A 1400 kg car moving westward with a velocity of 15 m/s collides with a utility pole and is brought to rest in 0. 30 s. What is the force exerted on the car during the collision?

A 2250 kg car traveling west slows down uniformly from 20. 0 m/s to 5. 00 m/s. How long does it take the car to slow down if the force on the car is 8450 N to the east?