Physics: Forces and the Laws of Motion Flashcards
What is the SI unit of force?
Newton
What is the English unit of force?
Pound
How many pounds per Newton are there?
0.225lb=1N
How many Newtons per pound are there?
4.448N=1lb
How do you derive Newtons from smaller SI units?
Newton = Kilogram x Meters per Second^2
Is force a vector or a scalar quantity?
Vector
What is Newton’s First Law?
An object at rest remains at rest, and an object in motion remains in motion, unless acted on by an outside force.
What is described by Newton’s First Law?
Inertia
What is the net force of an object?
The vector sum of all forces acting on an object
What is the net force of a car travelling at a constant velocity?
0N
What is Newton’s Second Law?
F=MA; Force=Mass x Acceleration
Why do you need to know Newton’s Second Law?
For Ma. Because if you don’t learn Newton’s Second Law, you will fail physics, and if you fail physics, you won’t be able to graduate, and if you can’t graduate, you will have to work at McDonalds. If you have to work at McDonalds, you will have to live in a dirty trailer park, and if you have to live in a dirty trailer park, you will start doing drugs, and if you start doing drugs you will die and leave you ma all alone with no one to take care of her when she gets old.
What is Newton’s Third Law?
Every action has an equal and opposite reaction
What are the four field forces in order from strongest to weakest?
Strong nuclear Force, Electromagnetic force, weak nuclear force, Gravity
What is the name of the force that stops us from going through the earth? (hint: it is the reaction to contact with the ground)
The force normal
What is the friction that stops an object from moving?
Static friction
What is the frictional force that retards the movement of an object in motion?
Kinetic friction
A bag of sugar has a mass of 2.26 kg. What is its weight in newtons on the moon where the acceleration due to gravity is one-sixth that of Earth?
3.70 N
The force of air resistance acting on a certain falling object is roughly proportional to the square of the object’s velocity. If the object falls fast enough, will the force of the air resistance eventually exceed the weight of the object and cause the object to move upwards? Explain.
No, because the object will just have reached equilibrium where the net force is 0, and will be falling at a constant velocity known as terminal velocity.
What is the equation to find the gravitational potential energy?
GPE = mass x gravity x height
What is the equation for elastic potential energy?
1/2 x spring constant x distance compressed or stretched^2
How do you find the spring constant?
distance compressed/force needed to compress the spring to that distance
