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Chapter 2 Physic
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Gravity
Terms in this set (20)
What is the net force on a cart that is pulled to the right with 110 pounds and to the left with 30 pounds?
F = 80 lb
What did Galileo demonstrate in his Leaning Tower of Pisa experiment?
He demonstrated that light and heavy objects gain the same amount of speed when falling.
How much support force acts on a 200-N girl standing on a weighing scale?
200 N
What is the net force on a crate sliding at an unchanging speed when pushed with a steady force of 75 N?
zero
Consider the video demonstration that you just watched. Which of the following changes would make it more likely for the ball to hit both the white can and the green can?
By Newton's first law, after it has left the circular track, the ball will travel in a straight line until it is subject to a nonzero net force. Thus, the ball can only hit the white can, because that is the only can in the ball's straight-line path.
When Dr. Hewitt pulls the tablecloth, what happens to the items on the tablecloth?
They tend to stay where they were.
When Dr. Hewitt pulls the tablecloth, why do the items on the tablecloth do what they do?
Inertia makes them stay at rest.
You tell your friend about the neat tablecloth trick that Dr. Hewitt demonstrated. Your friend tries to repeat this trick at home and later complains to you that it failed. Which of the following is most likely the reason that it failed?
Your friend pulled the tablecloth too slowly.
What is the net force on a cart that is pulled to the right with 120 pounds and to the left with 30 pounds?
120 lb - 30 lb = 90 lb.
F= 90 lb
Rank the magnitudes of the net force on the block from most to least in the four situations, A, B, C, and D.
Most (10N <-------A------>5N)(1N<----C---->4N)(10N<--------B------>8N)(3N<---D---->4N)
Consider a pair of forces, one having a magnitude of 20 N and the other a magnitude of 12 N. What maximum net force is possible for these two forces?
Fmax = 32 N
What is the minimum net force possible?
Fmin = 8 N
A different scaffold that weighs 400 N supports two painters, one 500 N and the other 400 N. The reading in the left scale is 800 N.
The top will have to be equal to the pull .
T= 500 N
When you flip a coin in high - speed airplane, it behaves as if the airplane were at rest. The coin keeps up with you
Inertia in action
Inertia
Property of things to resist changes in motion
Newton's first law of motion (The law of inertia)
Every object continues in a state of rest or of uniform speed in a straight line unless acted on by a nonzero net force.
Force
In the simplest sense, a push or a pull
Net Force
The vector sum of forces that act on an object
Mechanical equilibrium
The state of an object or system of objects for which there are no changes in motion. In accord with Newton's first law, if at rest, the state of rest persists. If moving , motion continues without change.
Equilibrium rule
For any object or system of objects in equilibrium, the sum of the forces acting equals zero. In equation form EF=0
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