Unit 1 (Kinetics)
The odometer in car measures this (distance or displacement).
What is distance? (The odometer measures the total miles traveled in the car, not the displacement from where it started)
This is a state in which opposing forces or influences are balanced.
What is equilibrium?
This is defined as the measure of energy transfer that occurs when an object is moved over a distance by an external force at least part of which is applied in the direction of the displacement and is represented by the equation Fd.
What is work?
If an object has a total kinetic energy of zero, this is the total momentum of the object.
What is zero? (Nothing is moving, so the total momentum is zero.)
If the velocity of a car is non-zero and constant, can the acceleration of the car be zero?
What is yes? (The velocity does not change, so acceleration is zero)
This law relating to springs is represented by the equation Fs = -kx.
What is Hooke's law?
A box being pulled up an incline by a rope has this many forces acting upon it (including friction).
What is four? (Friction, tension, normal, and gravity)
This type of collision involves two objects colliding, then sticking together and becoming one object. During the collision, the maximum amount of energy is lost and momentum is conserved.
What is a perfectly inelastic collision?
You throw a ball straight up in the air. After it leaves your hand, it has the most acceleration at this point.
What is everywhere? (The only acceleration the ball experiences is from gravity)
A person stands in an elevator weighing a cheeseburger with a kitchen scale. The mass of the cheeseburger is 0.150 kg. The scale reads 1.14 N. This is the weight of the cheeseburger.
What is 1.47 N? (W=mg, W= (.150)*(9.8 ms), W= 1.47 N)
A car traveling 80 km/hr can brake to a stop in 30 m. If the car is traveling 160 km/hr, this is the new stopping distance.
What is 120 m? If speed doubles, stopping distance quadruples. (Fd= 1/2mv^2)
Momentum is conserved in this type of collision.
What is every type of collision?
From the same height and at the same time, one ball is dropped and another is fired horizontally. This one will hit the ground first.
What is both at the same time?
The ratio between the force necessary to move one surface horizontally over another and the pressure between the two surfaces.
What is the coefficient of friction?
Three identical blocks each take a different path from a height h to the ground. Block A is released from rest and falls vertically. Block B is released from rest and slides down a frictionless incline. Block C is projected horizontally with an initial speed v. This block has the greatest speed.
What are all of them?
A 0.75 kg cart (#1) is pulled with a 1.25 N force for 1 second; another 0.75 kg cart (#2) is pulled with a 2.5 N-force for 0.50 seconds. This cart has the greatest acceleration.
What is Cart 2? (Acceleration depends on mass and force. The carts have equal mass, but Cart 2 has the greater force.)
A ball rolling at 5 m/s uniformly accelerates at 6 m/s^2 for 7 seconds. This is the final velocity.
What is 47 m/s? (Vf= Vi + at, Vi= 5, a=6, t=7, 5+7*6= 47)
A 1000N person is riding in an elevator on top of a scale. At one part of the trip, they look down and see that the scale reads 1200N. This is the acceleration of the elevator.
What is 1.96ms^2? (Fg=Mg, 1000/9.8 = M (9.8)/9.8, 102kg= M, 1200-1000=Ma, 200/102= 102a/102, a= 1.96ms^2)
A force of 30 N in lifts a load of 2 kg to a height of 10 m. This is the work done by the force.
What is 300 J? [W= Fd, F= 30, d (height)= 10, 30*10= 300]
A hockey player applies an average force of 95.0 N to a 0.25 kg hockey puck for a time of 0.10 seconds. This is the impulse experienced by the puck.
What is 9.5 N/s? [Impulse is determined by the equation F*t (95.0 * 0.10).]
(TWO PARTS)
Part 1:
Jennifer, who has a mass of 50.0 kg, is riding at 35.0 m/s in her red sports car when she must suddenly slam on the brakes to avoid hitting a deer crossing the road. She strikes the air bag, that brings her body to a stop in 0.500 s. This is the average force does the seat belt exert on her.
Part 2:
If Jennifer had not been wearing her seat belt and not had an air bag, then the windshield would have stopped her head in 0.002 s. This is the average force the windshield would have exerted on her.
Part 1:
What is 3500 N? (F= mass*change in velocity/time, F= 50*35, F= 3500 N)
Part 2:
What is 875,000 N? (F= mass*change in velocity/time, F= 50*35/0.002, F= 875,000 N)