DEFINITIONS
define Force
a push or pull
what are the 3 laws of motion?
1. inertia
2. f = ma
3. equal and opposite reaction...
give an example of an object with Stable Equililbrium
square... table 4 legs...
Henry is pushing a 15 kg box at an acceleration of 3.4 m/s^2. What was the force he exerted?
F = ma
F=(15)(3.4)
F= 51 N
define static friction
resistance to START sliding
What is definition of inertia?
objects tendency to remain in rest or motion, unless acted on by a force.
define Neutral Equilibrium
when the object rolls or turns over and the center of Gravity does not change...
ie. ball, rod, cylinder...
A piano needs to be moved in Sara's living room. The piano weighs 400 pounds, and has a kinetic coefficient of friction of 0.21. What is the Force required to keep the piano moving?
F= usFN
F= (0.21)(400pounds)
F= 84 pounds of force.
4 ways to reduce friction
define Gravitation
attractive force that exists between ANY two masses!
Give an example of Newton's 3rd Law of Motion
walking - ground and feet equal and opposite..
sitting in a chair - equal forces going down and up...
define Static Equilibrium
how an object rests normally without an outside force acting upon it... (stable equi. unstable equi.or neutral equi)
Heysel is pushing a 100 kg shopping cart with groceries. She is applying a force of 30 N, and the cart is experiencing 6 N of friction. Please find the acceleration of the cart.
∑Fx= max
24 = 100a
a= 0.24 m/s2
A force may be applied anywhere along its line of action without changing its effect… Different ways of moving an object – pushing or pulling – but same affect.
define Net Horizontal Force
If force is 10N, and Valeria wants to move an object with mass of 17 kg, what will be the object's acceleration?
F=ma
10=17a
a=.59 m/s2
define Unstable.
(not unstable equilibrium!)
when the CG lies outside the base of support.
Isis is pushing a 100 kg shopping cart with groceries. She is applying a force of 30 N, and the cart is experiencing 6 N of friction. Please find the acceleration of the cart. Then find the distance she is able to go in 45 seconds.
d= vot + 1/2(a)t2
d= 0 + 1/2(0.24)(452)
d= 243 m
What is the SI unit of Force ?
Newton!
define Friction
Please sing a portion of your Newton's Laws of Motion Song.
(:
Give an example of an object with neutral equilibrium.
basketball, cylinder, bowling ball, etc....
Brayan needs to move his couch. It has a mass of 1,234 kg and he exerts a force of 20 N on the couch. The couch and the floor have a friction force of 11 N. If he pushes the couch for 10 seconds, how far did he move it?
∑F = 20-11 = 9
F = ma -> 9 = (1234)(a) -> a=.007 m/s2
d = 0 + 1/2(.007)(102)
d= .35 m
Please describe what happens when you need to move a car that has a dead battery. Include how static and kinetic friction are affected as you continue to exert force.
If the car is at rest, and you begin to exert a force, you will be experiencing static friction. Static friction is always higher than kinetic friction. Right before the car moves, the static friction is at a maximum! and then right when it starts to move the static friction is converted into kinetic friction. It will be easier to keep the car moving than it was originally to set it into motion.