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