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19 terms

Impulse-Momentum Flashcards

This set of cards deals specifically with impulse-momentum vocabulary, concepts and quick calculations. Leave "term first" on as many of the questions cannot be answered from the definition alone.
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momentum
an object's mass in motion, determined by finding the product of the mass and velocity of an object
impulse
the force applied over a period of time which is necessary to change an object's momentum
conservation of momentum
in the absence of a net external force (in a closed system), the momentum of an object or system of objects remains unchanged
impulse-momentum theorem
in order to change an object's momentum, an impulse is necessary
closed system
no external forces are acting on the system
elastic collision
when two objects bounce off of each other and remain two objects (two objects in the initial state and final state); momentum is conserved in the system
inelastic collision
when two objects stick together and become on object; momentum is conserved in the system
system
the object or group of object's we are talking about
conserved
term applied to a physical quantity that remains unchanged during interactions (does not
change from beginning to end)
explosion
when one object becomes two objects; momentum is conserved in the system
Which has greater momentum: a train at rest or a moving skateboard?
Skateboard; since the train is not moving, it has no momentum. Since the skateboard has mass and is moving, it does have momentum.
Cars were previously manufactured to be as sturdy as possible, whereas today's cars are designed to crumple upon impact. Why?
By crumpling, the time of the collision is extended and so less force must act on the car to slow it to a stop, which is better for the passengers who will also feel less force.
How long must a 100 N net force act to produce a change in momentum of 200 kg·m/s?
2 seconds
Why are padded dashboards in cars are safer in an accident than non-padded ones?
Padded dashboards increase the impact time which decreases the impact force.
A 150 g baseball is thrown toward home plate with a speed of 40 m/s. The batter hits the ball directly back at the pitcher with a speed of 50 m/s. What is the change in momentum of the ball?
13.5 kg m/s
When jumping from a significant height, why is it advantageous to bend your knees when landing?
By bending your knees, you increase the impact time and decrease the impact force.
Which is larger: the impulse required to stop an object or the impulse required to rebound an object?
The impulse required to rebound an object. The impulse required to bring an object to a stop and then to "throw it back again" is greater than the impulse required merely to bring the
object to a stop.
The impulse-momentum relationship is a direct result of which of Newton's Laws of motion?
Newton's 2nd law
A 1500 kg car is rolling at 2.0 m/s. You would like to immediately stop the car by firing a 200 kg blob of sticky clay at it. How fast should you fire the clay?
Fire the clay at a speed of 15 m/s