physics 2/23-3/7
Which of the following lists correctly gives, in increasing order, the height of the high tides that occur during particular lunar phases? (Ties are denoted by parentheses.)
(first quarter, third quarter), (new, full)
If one person is pushing to the right on a 300-kg cart with a force of 200 N, and another person is pushing to the left on the same cart with a force of 100 N, what is the acceleration of the cart?
.33 m/s/s
In a simple machine, how much work is done when an input of 10 N acts over a distance of 5 m
50 J
how much times passes between low tide and high tide
6 hours
Suppose we replace the mass in the video with one that is four times heavier. How far from the free end must we place the pivot to keep the meter stick in balance
90 cm (10 cm from the weight
Why does the bowling ball behave the way it does the first time Dr. Hewitt lifts the bowling ball near his teeth and lets go
All of the initial energy of the ball was converted completely back to potential energy when the ball returned.
The crew of a cargo plane wishes to drop a crate of supplies on a target below. To hit the target, when should the crew drop the crate? Ignore air resistanc
Before the plane is directly over the target
Is it easier for a circus performer to balance a long rod held vertically with people hanging off the other end, or the same long rod without the people at the other end, and why
It is easier for the performer to balance a long rod held vertically with people at the other end because the rotational inertia is greater
Is it easier to balance a long rod with a mass attached to it when the mass is closer to your hand or when the mass is farther away?
It is easier when the mass is farther from your hand
What was the cause of perturbations discovered in the orbit of the planet Uranus? What later discovery did this lead to
Neptune caused the perturbations, and later Pluto was discovered
Why does the rotational inertia of the rod with the attached mass closer to your hand compare the way it does with the rotational inertial of the rod with the attached mass farther away
Rotational inertia depends on whether the mass is farther or closer to the point of rotation. The farther the mass is, the higher the rotational inertia
Why does the gravity in the Space Shuttle compare with the gravity on Earth the way it does?
The Space Shuttle is about the same distance from the center of the Earth than from the surface of the Earth
Why do the astronauts in the Space Shuttle float around
The Space Shuttle is in free fall, so the shuttle and the astronauts inside it are continuously falling toward the Earth. They thus experience apparent weightlessness.
Object A has three times as the mass of object B. Identical forces are exerted on the two objects. Which statement is true?
The acceleration of object B is three times that of object A
What happens the second time Dr. Hewitt lifts the bowling ball near his teeth and gives it a push
The ball leaves Dr. Hewitt and returns to him, going past the point where it was released
What happens the first time Dr. Hewitt lifts the bowling ball near his teeth and lets go
The ball returns to Dr. Hewitt, stopping almost exactly at the point where it was released
Consider the video demonstration that you just watched. A more complete explanation of what you saw will be possible after covering Newton's laws. For now, consider the following question: How would the result of this experiment change if we replaced the ball with another one that had half the mass? Ignore air resistance.
The ball would still land in the cart.
Why does the bowling ball behave as it does when Dr. Hewitt lifts it and gives it a push
The extra energy from the push is converted into kinetic energy, which is then converted into more potential energy at the end of the motion than the ball had when it was released
Why would a bowling ball and a small marble fall down to the surface of the Moon at the same rate
The force of gravity is proportional to the object's mass
How does the rotational inertia of the rod with the mass toward the bottom compare with the rotational inertia of the mass toward the top
The rotational inertia of the rod with the mass closer to the top is greater than the rotational inertia of the rod with the mass closer to the bottom
How does the torque due to the weight of one side of the broom exerted around the balance point compare with the torque exerted by the weight of the other side of the broom around the balance point
The torque due to the weight of the shorter side (the bristles of the broom) is equal in magnitude to the torque due to the weight of the longer side, and opposite in direction
A parachutist is falling toward the ground. The downward force of gravity is exactly equal to the upward force of air resistance. Which statement is true
The velocity of the parachutist is not changing with time
which has greater kinetic energy
a car of half the mass traveling at 60
A hydraulic press, like an inclined plane, is capable of increasing energy.
always false
Where is the center of gravity of the broom that Dr. Hewitt holds up
at the balance point
Earth's gravitational field is strongest at _______.
earths surface
Consider the video you just watched. Suppose we replace the original launcher with one that fires the ball upward at twice the speed. We make no other changes. How far behind the cart will the ball land, compared to the distance in the original experiment
four times as far
The experimenter from the video rotates on his stool, this time holding his empty hands in his lap. You stand on a desk above him and drop a long, heavy bean bag straight down into his hands. What happens
he spins slower
how do the high tides during a full moon compare to those at a new moon
high tides at full are the same and new
How is a flywheel constructed to maximize its rotational inertia
most of the mass is concentrated far from the axis
If the string that holds a whirling can in its circular path breaks, what kind of force causes it to move in a straight- line path: centripetal, centrifugal, or no force? What law of physics supports your answer?
no force; newtons first law
Imagine that Earth had an identical twin planet, "Farth", which is twice as far away from the Sun as Earth is. Compared to the force of gravity that Earth exerts on the Sun, how strong is the force of gravity that Farth exerts on the Sun
one-fourth as strong
Suppose the Sun suddenly shrunk, reducing its radius by half (but its mass remaining the same). The force of gravity exerted on the Earth by the Sun would _________.
remain the same
As soon as a bowling ball rolls off the edge of a table its horizontal component of velocity
remains constant
Inertia depends on mass; rotational inertia depends on mass and something else. What
the distribution of mass about the axis
How does the force of gravity between two bodies change when the distance between them is doubled?
the force decreaes to 1/4 its inital value
Why doesn't the force of gravity change the speed of a satellite in circular orbit
the force is at a right angle to the velocity
What happens to the force of attraction between two planets when the masses of both are doubled
the force quadruples
how does the gravity in the space shuttle compare with the gravity on the earths surface
the gravity is apro
If you stood on a planet having a mass four times that of Earth, and a radius two times that of Earth, how much would you weigh on that planet?
the same as your weight on Earth
each day
there are two high tides and two low tides
high tide can occur
when the moon is high overhead
if there were no moon, would there still be tides on earth
yes because the suns gravity still has an influence
