PHYSICS TEST 2

To rotate a stubborn screw, it is best to use a screwdriver that has a

A wide handle If it was a wrench, a long handle

A circus diver drops from a high pole into water far below. When he is halfway down

A) he has gained an amount of kinetic energy equal to half his initial potential energy B) his kinetic energy and potential energy are equal C) his potential energy is halved D) all of the above D

The greater efficiency achieved with the curved blades of a Pelton wheel is due to

Bouncing

A bicycle that travels twice as fast as another when braking to a stop will skid

Four times as far. KE=.5mv^2

Consider a moon that orbits one of our most distant planets in an elliptical path. The distance that the moon covers each day is

Greatest when closest to the planet

Padded dashboards in cars are safer in an accident than non-padded ones because passengers hitting the dashboard encounter

Lengthened time of contact. Lengthens the time to get to the plastic part.

A 5000-kg freight car collides with a 10,000-kg freight car at rest. They couple upon collision and move at 2 m/s. What was the initial speed of the 5000-kg car?

M before = M after (5000)(x)+(10000)(0)=15000(2) 6

A primary difference between momentum and kinetic energy is

Momenta can cancel; Kinetic energy cannot M is a vector so it can change directions. A neg plus a positive can make it cancel. Squaring gets rid of direction. Kinetic energy is not a vector.

If an all-electric car has kinetic energy, then it also must have

Momentum M= mv KE= .5mv^2

If a Ping-Pong ball and a golf ball both move in the same direction with the same amount of kinetic energy, the speed of the Ping-Pong ball must be

More than the golf ball

If a monkey floating in outer space throws his hat away, the hat and the monkey will both

Move away from each other, but at different speeds

After rolling halfway down an incline, a marble's kinetic energy is

The same as its potential energy

The work you do when pushing a shopping cart twice as far while applying the same force is

Twice as much

A difference between linear momentum and angular momentum involves

Two types of speed and a radial distance

If a satellite's radial velocity is zero at all times, its orbit must be

circular

If a turntable's rotational speed is doubled, then the linear speed of a pet hamster sitting on the edge of the record will

double

If Earth rotated more slowly about its axis, your weight would

increase

Each of us weighs a tiny bit less inside the ground floor of a skyscraper than we do on the ground away from the skyscraper because the

mass of the building above slightly attracts us upward

The main reason ocean tides exist is that Moon's pull is stronger

on water closer to it than on water farther away

According to Newton, when the distance between two interacting objects doubles, the gravitational force is

one quarter (m1Xm2)/d^2

Two people are balanced on a seesaw. If one person leans inward toward the center of the seesaw, that person's end of the seesaw tends to

rise

The chef at the infamous Fattening Tower of Pizza tosses a spinning disk of uncooked pizza dough into the air. The disk becomes wider during its flight, while its rotational speed

slows

The main reason a person weighs less at the equator than at the poles involves the

spin of the earth

The moon does not crash into earth because

the moon has sufficient tangential speed

Consider two flywheels of the same size and shape, but one with twice the mass. Rotational inertia of the more massive one is

two times greater