Physics Chapter 6-8
The rate of doing work, or transforming energy, can be measured in
watts
When a twirling ice skater brings her arms inward, her rotational speed
increases
What is the quantity used to measure an objects resistance to changes in rotational motion?
moment of inertia
Horses that move with the fastest linear speed on a merry-go-round are located
near the outside
A large heavy truck and a small baby carriage roll down a hill. Neglecting friction, at the bottom of the hill, the baby carriage will have a greater
none of these
Energy could be best described as
the capactiy to do work
It is correct to say that impulse is equal to
the change in momentum it produces
A freight train rolls along a track with considerable momentum. If it rolls at the same speed but has twice as much mass, its momentum is
doubled
On a balanced seesaw, a boy three times the mass as his partner sits
1/3 the distance from fulcrum
How much work is required to lift a 2.5 kg object 6.0 meters?
150J
The center of gravity of a circular disk of sheet metal is
at the center of the disk
A car travels in a circle with constant speed. The net force on the car is
directed toward the center of the curve
The type of energy that a swining pendulum has at the high point of its swing is
gravitational
The tyoe of energy that a swinging pendulum has at the low point of its swing is
kinetic
When you are in the way of a fast moving object and you can't get out of its way, you will suffer a smaller force of impact if you decrease its momentum over a
long time
Two objects have the same size and shape, but one is much heavier than the other. When they are dropped simultaneously from a tower, they reach the ground at the same time, but the heavier one has a greater
momentum
Which moves faster in m/s on a merry go round: a horse on the inside or a horse on the outside?
outside horse
A rifle recoils while firing a bullet. The speed of the rifle's recoil is small because
rifle has much more mass than the bullet
A torque acting on an object tends to produce
rotation
The rotational inertia of your leg is greater when your leg is
striaght
Three cars, x, y, z, begin accelerating from rest, at the same time, car x is more massive than car y, which is more massive than car z. The net force exerted on each car is identical. After 10 secs which carhas the most amount of momentum?
they all have the same momentum
If you push an object a given distance,while applying twice the force, you do
twice as much work
When objects stick together after colliding, the collsion is completely elastic.
false
To catch a ball, a baseball player extends the hand forward before impacts with the ball and then lets it ride backward in the direction of the ball's motion. Doing this reduces the force of impact on the player's hand principally because the
time of impact increased
An object lifted 10 meters gains 200j of potential energy. If the same object is lifted 20 meters, its energy gain is
twice as much
A 3kg blob of putty moving at 3m/s slams into a 4kg blob of putty at rest. Calculate the momentum of the 2 stuck together blobs of putty immedialty after colliding
9 kg m/s
The conservation of momentum is most closely realted to
Newtons 3rd law
The conservation of momentum is most closely related to
Newtons 3rd law
A piece of mud flies off the rim of a bycicle wheel. In what direction will it be going immediately after leaving the wheel? (Ignore gravity in this short time interval.)
On a line at a tangent to the edge of the wheel
Which of the following principles explains why guns recoil
Consservation of momentum
In order to quadruple an objects kinectic energy, we must
double it
A 1-kg chunk of putty moving at 1 m/s collides and sticks to a 5-kg bowling ball initially at rest. The bowling ball and putty then move with a momentum of
1kgm/s
A moving object triples in mass, how much more momentu, does it have?
3x more momentum since the momentum directly depends on the mass.
What form(s) of energy does the falling rubber ball have when it is halfway down?
Both kinetic and gravitational
When a rigid body rotates about a fixed axis all the points in the body have the same centripetal acceleration.
False
The moon is moving clackwise in a circular orbit around the Earth. Imagine if gravity was shut off, throughout the solar system, at the instant the moon is in the poistion shown. How would the moon move, after gravity was shut off.
In the direction of the down arrow, in a straight line.
The impulse momentum relationship is a direct result of
Newtons 2nd Law
A 5kg ball collides head-on with a 10kg ball, which is stationary. The collision is inelastic. What statement is true?
The magnitude of the change in velocity the 5 kg ball experiences is greater than that if the 10kg ball.
A ball can be rolled down 3 different ramps. The final elevation loss of each ramp is the same. Neglecting friction, for which ramp will the speed of the ball be at the highest at the bottom?
The speed of the ball will be the same for all ramps.
A smaller car and a large truck collide head-on. During the collision the small car experiences
a much larger acceleration than the truck
When doing somersaults, you'll more easily rotate when your body is
balled up
You're driving down the highway and a bug spatters into your windshield. Which undergoes the greater change in momentum during the time of contact?
both are the same
A coin and a ring roll down an incline starting at the same time. The one to reach the bottom first will be the
coin
It is correct to say that impulse is equal to
the change in momentum it produces.
A merry go round spins freely when Janice moes quickly to the center along a raduis of the merry go round. Its true to say that
the moment of the inertia of the system decreases and the angular speed increases
For a system in mechanical equilibrium
the resultant forces and torques must both be zero
A tall tree and short tree (both having the same wwidth and density) are cut at the base at the same time and begin tipping over. which tree hits the grounf first?
the small tree