Vocab
What is the rate of change of velocity called?
Acceleration
Write the formula for velocity/speed
v=d/t
A 2 kg ball moves at 3 m/s. What is its momentum?
6 kg*m/s
What direction does centripetal force point?
towards the center of the circle
When a car makes a sharp turn, why do passengers feel like they’re being pushed outward?
Inertia resists the change in direction — there’s no outward force, only centripetal force inward.
What type of motion occurs when an object moves in a circle?
Circular Motion
Write the formula for acceleration.
a=Δv/Δt
A 1 kg object moves in a circle of radius 2 m at 4 m/s. Find centripetal force.
8N
If no external forces act, what happens to total momentum in a system?
It stays constant (conservation of momentum)
If a force acts for a longer time, what happens to impulse?
It increases (since J=FΔtJ = FΔtJ=FΔt)
What is the inward force that keeps an object moving in a circle?
Centripetal Force
Write the formula for centripetal acceleration.
ac=v2/r
A 1000 kg car moving at 20 m/s crashes and stops in 0.5 s. What is the impulse?
20,000 N*s
What is conserved in both elastic and inelastic collisions?
Momentum
What does a large impulse mean?
A big change in momentum
What is the product of mass and velocity called?
Momentum
Write the formula for centripetal force.
Fc=mv2/r
Two objects (1 kg at 3 m/s and 2 kg at -1 m/s) collide and stick. Find final velocity.
1/3 m/s
What is the difference between elastic and inelastic collisions?
Elastic: kinetic energy conserved; Inelastic: kinetic energy not conserved
Why do crumple zones make cars safer during collisions?
They increase collision time, reducing force on passengers (since F=Δp/Δt)
What is the change in momentum called?
Impulse
Write the impulse-momentum equation.
J=ΔP
J=FΔt
A 0.5 kg ball moves at 4 m/s around a 1 m circle. What is centripetal acceleration
16 m/s/s
Why do you feel pushed outward when turning in a car?
Inertia — your body resists the change in direction
Why do astronauts in orbit feel weightless even though gravity is still acting on them?
They’re in continuous free fall around Earth — gravity provides centripetal force, but no normal force acts on them.