Forces
What is force?
a push or pull acting on an object
State Newton's first law.
an object in motion will remain in motion and an object at rest will remain at rest unless acted upon by another force.
What is the formula for Newton's second law?
F=MA
A player hits a ball with a bat. If the bat exerts a force on the ball, what is the reaction force?
The force of the ball against the bat
Why is the Earth’s gravitational force acting on the moon stronger than the Sun’s
Because the Earth is closer to the moon than the Sun
What is the SI unit for force?
newton
Inertia causes a moving object to:
keep moving if its moving or stay unmoving if its not moving.
________________________ is defined as a change in speed or change of direction, including slowing down, starting, and coming to a stop
Acceleration
A heavy truck and a light passenger car are moving at the same speed. Do they they have the same momentum? If not, which has more momentum?
No, the heavy truck has more momentum.
Which force he keeps solid objects from falling through solid surfaces?
The normal force
What force causes an object sliding across a table to slow down?
Friction
What efect does an unbalanced force have on an object?
It can cause an object to speed up, change direction or slow down.
other acceptable answers:
- It causes a change in motion
- It causes a change in velocity
The more mass an object has, the more ____________________ is required in order to cause
acceleration.
force
What is the formula for calculating momentum?
Momentum = mass × velocity
or
P=MV
Do objects falling to earth fall at a constant rate or do they accelerate as they fall?
accelerate as they fall
If two movers are moving a sofa and one movers is pushing with a force of 25N and the other is pulling with a force of 20N, what is the net force acting on the sofa?
45N
The inertia of an object depends on its ____________.
Mass
_________________________ describes how everyday objects as well as very large objects like planets move.
Classical mechanics
The Law of Conservation of Momentum states:
The total momentum before a collision is equal to the total momentum after a collision.
If you are on a bus and someone asked you if you were moving, the answer would depend on what?
Your frame of reference.
If 2 soccer players try to kick a ball at the same time in opposite directions, one with a force of 75N and one with a force of 150N, what is the net force acting on the ball?
75N
What is always required to overcome inertia?
An unbalanced force
_________________________ deals with the laws of physics at very, very small scales. Interactions in are very odd, like particles being in many places at once.
Quantum mechanics
________________________ is the frictional force between objects before they start to move.
Static friction
According to Einstein, why do objects with mass exert a force of gravity on other objects?
Mass causes spacetime to curve, which dictates the motion of other objects.