Impulse Momentum and Energy Transformation Flashcards
efficiently elastic material example
rubber
steel
cork
one that has the right combination of strength and elasticity for a particular application
can regain their shape after being stretched or compressed
efficiently elastic material
mass in motion
momentum
intertia in motion
momentum
a lot of momentum means a lot of ___
oomph
momentum formula
mass x velocity
two types of momentum
linear momentum
angular momentum
angular momentum formula
L = Iw
SI unit of momenntum
kg m/s
the direction of the momentum is the same as ___
velocity
a vector that points in the same direction as the object’s velocity
monemtum
as such we can also write the momentum in terms of x and y components that is
px = mvx
py = mvy
he momentum towards the __and ___will have a negative sign.
left
down
what is newton’s second law of motion
an object acted upon by a constant unbalanced force, moves with constant acceleration in the direction of the unbalanced force
newton’s second law of motion formula
Funb = ma
to rewrite momentum in terms of newton’s second law of motion:
F = ma
F = m Δv/t = mΔv/t
Ft = mΔ
ft = Δ(mv) is also known as
impulse
change in momentum
impulse
impulse unit
J
is defined as the change in momentum of an object due to a force that is applied during a period of time
impulse
aside from J, impulse also the unit
N s
sually considered typically during collision (short period) or explosion
impulse
states that an impulse delivered to an object causes the object’s momentum to change.
momentum principle
a 1.3kg ball is coming straight at a 75 kg soccer player at 13 m/s who kicks it in the exact oppositedirection at 22 m/s with an average force of 1200N. How long are his foot and the ball in contact?
0.0379s
product of the force acting on an object over time during which the force acts
impulse
impulse momentum theorem formula
F = mΔv/t
impulse applied to the object is equal to the ___
change in momentum
states that the total momentum of an isolated system remains constant, unless an external force acts upon it
law of conservation of momentum
law of conservation of momentum formula
mava + mbvb = mava + mbvb
law of conservation of momentum states
in a closed and isolated system, the total momentum of the objects before a collision is equal to the total momentum of the objects after the collission
system where matter and energy do not enter or leave the system
closed, isolated system
is a brief interaction between two (or more) objects
collission
the word __ is used when the interaction time (Δt) is short relative to the rest of the motion
collission
during a collision, the objects exert equal and opposite forces on each other, we assume these “internal” forces are much larger than any ____ on the system
external
three types of collission
perfectly inelastic
elastic
inelastic
two object stick together after the collision so that their final velocities are the same
perfectly inelastic
conserved quantity in perfectly inelastic collision
momentum
the two objects bounce after the collision so that they move separately
elastic collision
what is conserved in elastic collision
momentum and kinetic energy
the two objects deform during the collision so that the total kinetic energy decreases, but the objects move separately after the collision
inelastic collision
conserved quantity in inelastic collision
momentum
energy of motion
kinetic energy
kinetic energy formula
1/2mv^2
J is also known as
kg m^2/s^2
two dimension collision of two objects formula
m1v1ix + m2v2ix = m1v1fx+m2v2fx
m1v1iy+m2v2iy = m1v1fy+m2v2fy
Which has a greater momentum—a truck with a mass of 2250 kg moving at a speed of 25 m/s or a car with amass of 1210 kg moving at a speed of 51 m/s?
car
A car accelerates from rest. In doing so the absolute value of the car’s momentum changes by a certain amount and that of the Earth changes by a larger amount.
False
The impulse-momentum relationship is a direct result of
Newton’s second law
A 5000-kg freight car moving at 2 m/s collides with a 10,000-kg freight car at rest. They couple upon collision and move away at
2/3 m/s
When a golf club hits a golf ball, the change in momentum of the ball is ___________ the change in momentum of the club.
equal to
Consider two carts, of masses m and 2m, at rest on an air track. If you push first one cart for 3 s and then the other for the same length of time, exerting equal force on each, the kinetic energy of the light cart is smaller than the kinetic energy of the heavy car.
T/F
False
Suppose the entire population of the world gathers in one spot and, at the sounding of a prearranged signal, everyone jumps up. While all the people are in the air, Earth recoils, like a rifle firing a bullet, with a change in momentum equal to and opposite that of the people.
T/F
True
If we consider Earth to be an isolated system (during the short time interval that the people jump up, this approximation is appropriate), then momentum must be conserved. So the momentum of Earth must be equal to and opposite that of the jumping people. Because of Earth’s large inertial mass, however, there is no perceptible motion.
If superman at rest in free space throws an asteroid that has more mass than superman, then which moves faster?
superman
A Toyota (small car) strikes a Mack truck (large truck) head-on. They stick together after the collision. Defining the system as the car plus the truck, total momentum and total energy are conserved.
T/F
True
Assuming that the drivers do not apply the brakes and thus the system is isolated, both total momentum and total energy are conserved. Some kinetic energy is dissipated into the deformation of the car and truck so kinetic energy is not conserved.
Correct answer: True
Padded dashboards in cars are safer in an accident than non-padded ones because passengers hitting the dashboard encounter
: lengthened time of contact
A person is standing on a roller blades and is holding a heavy medicine ball. If he throws the ball horizontally to the right, what will be the resulting motion?
: to the left
A large heavy truck and a small baby carriage roll down a hill. Neglecting friction, at the bottom of the hill,the baby carriage will likely have
less momentum.
Whether a truck comes to a stop by crashing into a haystack or a brick wall, the impulse is
both the same
A golf ball is fired at a bowling ball initially at rest and bounces back elastically. Compared to the bowling ball, the golf ball after the collision has less momentum but more kinetic energy.
T/F
True
The golf ball bounces back at nearly its incident speed, whereas the bowling ball hardly budges. Thus the change in momentum of the golf ball is nearly -2mv, and the bowling ball must gain momentum +2mv to conserve momentum. However, since the mass of the bowling ball is much larger than that of the golf ball, the bowling ball’s velocity and hence its kinetic energy are much smaller than those of the golf ball.
Skelly the skater travelling at high speed needs a certain amount of force to stop him. More stopping force is needed if he has
all of the above
The momentum change of an object is equal to the
impulse acting on it
A 90 kg halfback runs north and is tackled by a 120 kg opponent running south at 4 m/s. The collision is perfectly inelastic. Just after the tackle, both players move at a velocity of 2 m/s north. Calculate the velocity of the 90 kg player just before the tackle.
The velocity of the 90kg player just before the tackle is 10 m/s, North.
