scince Flashcards
What is a force?
a push or pull
What is the difference between mass and weight?
mass - the amount of matter in an object
weight - gravitational force/pull that gravity changes
What is the relationship between mass and inertia?
mass - the amount of matter in an object
inertia - resisting motion
* the more mass the more inertia
What does Newton’s 1st Law state?
an object that is at rest stays at rest unless acted upon by an external force
What does Newton’s 2nd Law state?
a force acting upon an object equals the object’s mass times acceleration
Fnet = m*a
How does acceleration change with increasing force?
force increases, acceleration increases
How does acceleration change with increasing mass?
mass increases, acceleration decreases
What two things does work require?
- force
- distance
In which direction must a force be applied in order to do work?
the same direction as the object
Is there any work done on an object when you lift the object over your head? Why or why not?
yes because object is moving up and the force is moving up
Is there any work done on the chair when you pick up a chair and carry it across the room? Why or why not?
yes because the force is up and then the chair is up as well
What are the units of force?
newtons
List two different units of work.
- joules
- N*M
What is power?
the work done in a certain time
List two different units of power.
- watts
- joules
When it takes more time for work to be completed, does this require more or less power?
less power
When it takes less time for work to be completed, does this require more or less power?
more power
What is the conversion factor between watts and horsepower?
1 hp = 746 w
1 w = 1/746 hp
A student applied a force of 12 N and moved the chair 2 meters. What question do you need to ask to determine the amount of power used?
how much time it took
For each of the following statements, identify whether the everyday or the scientific meaning of work is intended: Jack had to work against time as the deadline neared.
everyday
For each of the following statements, identify whether the everyday or the scientific meaning of work is intended: Jill had to work on her homework before she went to bed.
everyday
For each of the following statements, identify whether the everyday or the scientific meaning of work is intended: Jack did work carrying the pail of water up the hill.
scientific
Determine whether work is being done in the following example: a train engine pulling a loaded boxcar initially at rest.
yes
Determine whether work is being done in the following example: a tug of war that is evenly matched.
no
Determine whether work is being done in the following example: a crane lifting a car.
yes
If a neighbor pushes a lawnmower four times as far as you do, but exerts only half the force, which one of you does more work and by how much?
2 times more
