Physics I Exam 2 Ch 4-6 Terms

Newton’s First Law

An object at a constant velocity stays at this velocity until or unless acted upon by an external force.

Newton’s Second Law

F=ma

Newton’s Third Law

For every action there is an equal and opposite reaction

Gravitational Force equation

F=GM₁M₂/r²

What does a Newton (N) equal?

kg(m/s²)

Circumference of a circle

2πr

What are the 4 Fundamental Forces

1. Gravity

2. Strong Force

3. Weak Force

4. Electromagnetic Force

Describe the fundamental force gravity

The weakest force, for massive objects (planets)

Describe the fundamental force strong force

the bond that holds atoms together

Describe the fundamental force weak force

electroweak force that governs particle decay

Describe the fundamental force electromagnetic force

governs electricity and magnetism

What are the specific types of mechanical/gravitational forces

1. Normal Force F_n=mg

2. Gravitational Force for planets M₁M₂/r²

3. Frictional Force μF_n

4. Tension Force F=ma

What is the equation for Normal force?

F_n=ma

Frictional Force equation

μF_n

What does μ equal

coefficient of friction

What is a constant?

Something that doesn’t change (eg gravitational constant)

What is inertia?

The natural tendency of an object to remain at rest or in motion at a constant velocity. The mass of an object is a quantitative measure of inertia.

Inertial Reference frame

The frame of reference that is moving

Free body diagram

represents the object and the forces that act on it

Tension

opposite force

A system in equilibrium has no net force

True

A system not in equilibrium has net force

True

Kinetic Energy

KE= ½ mv²

Potential Energy

PE=mgh

Total Energy

KE+PE

If total energy =0, what is the equation

KE+PE=0

KE=-PE

Work

W=F⋅s

W= |F||s|cosθ

What does the s equal in the Work equation?

W=F⋅s

W= |F||s|cosθ

s=path length

What does the θ equal in the Work equation?

W=F⋅s

W= |F||s|cosθ

θ= angle between the force vector and the path (displacement vector)

Is a dot product a vector or scalar?

Always a scalar

What is a dot product?

a⋅b= a_xb_x+ a_yb_y

What is the Kinetic Force equation

F_KE= ½ mv_f² - ½ mv_o²

Work is not a change in Kinetic Energy

False

Momentum equation

p=mv

Total Work/Energy equation

ΔE_total=(½ mv_f²+mgh_f) - ((½ mv_o²+mgh_o)

Gravitational Potential Energy

the energy that an object has by virtue of its position. For an object near the surface of the earth.

Gravitational Potential Energy equation

W_gravity=mg(h_o-h_f)

What does a Joule equal?

J= N x m (Force times mass)

Power equation

Work/t = (F⋅s)/t = ΔE/t

Conservation of Energy

Initial Energy = Final Energy

acceleration equation

Δv/Δt

The 4 kinematic equations

centripetal force equation

F_c= mv²/r

centripetal acceleration

a= v²/r