Newtons Laws
Chapter 4
Chapter 4
What is Newtons first Law?
An object in motion will stay in motion unless acted upon by an unbalanced force
Law of Inertia
What is the term for a piece of a vector that points in either the horizontal or vertical direction?
component
What direction is an object accelerating while experiencing uniform circular motion
inward, towards center of circle
What is Hooke's law?
force is directly proportional to the distance of deformation
F= K*x
What is the centripetal force of a 70kg object when moving in circular orbit at a rate of 2m/s2?
Fc=m*ac
70*2= 140 Newtons
What is newtons seconds law?
the net force on a body is equal to the body's acceleration multiplied by its mass or, equivalently, the rate at which the body's momentum is changing with time
F = ma
What angle launch of a projectile would result in a range of 0 meters?
0 or 90
A ball being swung in a circle from a string because detached and flies outward away from the center of the circle. In circular motion the acceleration is inward so why does the ball fly outward?
inertia
Give one way a football player could increase his momentum?
mass increase (gain weight) or increase speed
What is the centripetal acceleration of a car moving at 27 m/s around a radius of 3 meters?
ac=v2/r
243 m/s2
What is Newtons 3rd law
For every action there is an equal and opposite reaction
action-reaction law
If an object sits on an inclined plane and no other object makes contact with the object, what is typically equal in magnitude to the component of the weight perpendicular to the plane?
normal force
What is the angle formed between the vectors of centripetal acceleration and centripetal force?
0 degrees
What are the units of k (spring constant)
N/m
What force is necessary to stretch an ideal spring with a spring constant of 120 N/m by .05 m?
F = k*x
100*.05= 5 N
What force is needed to give a mass of 15kg an acceleration of 5m/s2?
15kg*5m/s2= 75 Newtons
Ignoring drag, what is the x-component of the acceleration of a projectile?
0
What is the angle formed between the vectors of tangential velocity and centripetal force
90
What are the units of momentum?
kg*m/s
A force of 52Newtons is applied at an angle of 40 degrees to the horizon resolve into x and y components
Fx: 52Cos(40)= 39.83 N
Fy: 52Sin(40) = 33.42 N
What is the acceleration of a 60 kg mass when a 200 N force is applied to it?
A=F/m
200/60=3.333m/s2
There are two methods for finding vector components. The method that uses Pythagorean theorem and trigonometric identities is known as
analytical method
What are the units of angular velocity?
radians
the change in momentum is known as
impulse
A skier with a mass of 60kg is skiing down a snowy slope that has an incline of 30 degrees. Find the coefficient of kinetic friction for the skier if friction is known to be 25 N
Fn= mgCos(theta)
60*9.8*Cos(30)= 509.22
mu= fk/Fn 25/509.22 = .049