Schaub chapter 6
When the speed of your car is doubled, by what factor does its kinetic energy increase?
1/2mv^2. 4
A car traveling at a velocity v can stop in a minimum distance d. What would be the car's minimum stopping distance if it were traveling at a velocity of 2v?
4d. F*d= 1/2mv^2 2^2= 4
A ball is thrown straight up. At what point does the ball have the most energy? Ignore air resistance. At the highest point of its path. Just before it hits the ground. When it is first thrown. When the ball is halfway to the highest point of its path. Everywhere; the energy of the ball is the same at all of these points.
Everywhere; the energy of the ball is the same at all of these points. Total energy is conserved if only conservative forces act. KE+PE is constant
A bowling ball is dropped from a height h onto the center of a trampoline, which launches the ball back up into the air. More than h. The exact amount depends on the mass of the ball and the springiness of the trampoline. No more than h-probably a little less. Significantly less than h. Cannot tell without knowing the characteristics of the trampoline.
No more than h-probably a little less.
A satellite in circular orbit around the Earth moves at constant speed. This orbit is maintained by the force of gravity between the Earth and the satellite, yet no work is done on the satellite. No work is done because there is no gravity in space. No work is done if objects move in a circle. No work is done if the direction of motion is perpendicular to the force. No work is done if there is no contact between objects.
No work is done if the direction of motion is perpendicular to the force.
A ball is thrown straight up. Neglecting air resistance, which statement is not true regarding the energy of the ball? The potential energy decreases while the ball is going up. The kinetic energy decreases while the ball is going up. The kinetic energy increases when the ball is coming down. The potential energy decreases when the ball is coming down. The sum of the kinetic energy and potential energy is constant.
The potential energy decreases while the ball is going up.
Engines, including car engines, are rated in horsepower. The amount of work the engine can perform. The rate at which the engine can do work. The energy the engine needs to obtain from gasoline or some other source. The force needed to keep the engine running at a steady rate. The force needed to start the engine.
The rate at which the engine can do work. P=w/t
Conservative forces
do not depend on path. Gravity, elastic, electric. Ke+pe=constant.
Non conservative
path matters. Ke1+Pe1+WNc=Ke2+Pe2 WNc= Ffr(cos180)d --> (-Ffrd)