Physical Science - Chapter 3
What is the acceleration of free fall?
10 m/s/s
What is the weight of a 1-kilogram brick?
9.8 newtons
Is acceleration proportional to net force or does acceleration equal net force?
Acceleration is proportional to net force.
What is meant by free fall?
Air resistance doesn't affect the motion of a falling object.
The ratio of circumference/diameter for all circles is pi. What is the ratio of force/mass for freely falling bodies?
All freely falling objects have the same force/mass ratio and undergo the same acceleration at the same location.
Is acceleration directly proportional to mass, or is it inversely proportional to mass?
It is inversely proportional to mass.
If the mass of a sliding block is somehow tripled at the same time the net force on it is tripled, how does the resulting acceleration compare to the original acceleration?
It will be unchanged.
If the net force acting on a sliding block is somehow tripled, by how much does the acceleration increase?
It will triple.
the acceleration produced by a net force on an object is directly proportional to the net force, is in the same direction as the net force, and is inversely proportional to the mass of the object
Newton's Second Law
What two principle factors affect the force of air resistance on a falling object?
Speed and surface area
What is the acceleration of a falling object that has reached its terminal velocity?
The acceleration becomes zero.
Suppose you exert a horizontal push on a crate that rests on a level floor, and it doesn't move. How much friction acts compared to your push?
The friction is pushing to the opposite of where you are pushing the crate.
What relationship does mass have with inertia?
The greater an object's mass, the greater its inertia. They are directly proportional to each other.
Why doesn't a heavy object accelerate more than a light object when both are freely falling?
The ratio of weight to mass is the same for the both of them.
If two objects of the same size fall through air at different speeds, which encounters the greater air resistance?
There is less terminal speed for the heavier object.
What relationship does mass have with weight?
They are different from each other but they are directly proportional to each other. The greater the mass the greater the weight.
Distinguish between velocity and acceleration.
Velocity is the speed and direction an object is moving in while acceleration is the rate at which velocity changes with time.
As you increase the push, will friction on the crate increase also?
Yes it will.
Once the crate is sliding, how hard do you push to keep it moving at constant velocity?
You push as much as you did to get it moving.
When are you most aware of motion in a moving vehicle - when it is moving steadily in a straight line or when it is accelerating?
accelerating
the rate at which velocity changes with time; the change may be in magnitude or direction or both
acceleration
frictional resistance due to motion through air
air drag
motion under the influence of gravitational pull only
free fall
the resistive force that opposes the motion or attempted motion of an object past another with which it is in contact, or through a fluid
friction
the property of things to resist changes in motion
inertia
when two values change in opposite directions, so that if one increases and the other decreases by the same amount, they are said to be inversely proportional to each other
inversely
the fundamental SI unit of mass; one kilogram (symbol kg) is the mass of 1 liter(1) of water at 4 degrees C
kilogram
the quantity of matter in an object; more specifically, it is the measure of the inertia or sluggishness that an object exhibits in response to any effort made to start it, stop it, deflect it, or change in any way its state of motion
mass
Shake something to and fro and you're measuring its ___. Lift it against gravity and you're measuring its ___.
mass ; weight
the speed at which the acceleration of a falling object terminates because air resistance balances its weight
terminal speed
terminal speed with direction of motion (down for falling objects)
terminal velocity
the quantity of space an object occupies
volume
the force due to gravity on an object
weight