Momentum is a vector quantity, is ALWAYS conserved, and defined as the product of mass and velocity.
Momentum p has the units kg m/s or N s
p = m v
Find the momentum of a bowling ball of 8kg rolling at a velocity of 5 m/s. How fast would a golf ball with a mass of 60g have to be moving to have the same momentum?
Impulse J is a vector quantity that has the same units as momentum.
Impulse ­ Momentum Theorem: The impulse of a force acting on an object equals the change in momentum of that object.
J = F∆t = ∆p = mvf ­ mvi
F = ma = m ∆v = ∆p
∆t ∆t F∆t = ∆p A 0.042kg hollow raquetball that has an initial speed of 12.0m/s collides with the backboard of the court. It rebounds with a speed of 6.0m/s. Find the total impulse on the ball and if the contact time was 0.040s, what was the average force on the ball?
HW P. 157 # 60
a.) 7.5J
b.) 15J
c.) 7.5J
d.) v = 2.3m/s at 5m
v = 4.5m/s at 15m
HW QQ6.1
To masses m1 and m2, with m1 < m2, have equal kinetic energy. How do the magnitudes of their momentum compare?
P. 164 EX 6.1
a) not enough info b) p1 < p2
c) p1 = p2 d) p1 > p2
a) 13.5 kgm/s b) 6750N
A pitcher claims he can throw a 0.145kg baseball with as much momentum as a 3.0g bullet moving at a speed of 1500m/s. a.) Find the speed the baseball must be thrown at if the pitcher’s claim is valid. b.) Determine the kinetic energy of each object: the baseball and the bullet. SHOW WORK!
A 20kg object is acted on by a force as shown in the diagram. Find the impulse delivered to the block and the final velocity of the block if it started from rest.
Scott is sitting on frictionless ice and holding two heavy ski boots. Scott weighs 637N and each boot has a mass of 4.5kg. Scott throws both boots forward at the same instant at a velocity of 6.0m/s relative to him. What is Scott's resulting velocity?