CH6,7 and TRIG NEW Flashcards
What weighs about 1 N?
an apple
What weighs about 10N?
Large Textbook
or a 1 liter bottle of soda
What weighs 100N?
3 Gallons of milk
What weighs 1000N?
Mr. Nystrom wearing a backpack full of books
If you weigh 600N and are hanging on a rope, you are pulling down 600N on the rope. The rope is pulling ______
up 600N on you!
If you weigh 600N and jump off of a building, do you accelerate towards the earth?
Does the earth accelerate towards you?
YES, you accelerate toward the earth and YES the earth accelerates toward you (it is hard to see)
How can you think of gravity to help you “see” objects being pulled towards eachother?
Imagine a stretched spring between them. A spring between two cars may pull them both together at the same acceleration, but a spring between a car and a skateboard will mostly pull the skateboard more. MASS RESISTS ACCELERATION
Why don’t you see the earth move when you jump up?
It is so massive that it barely moves
If force = mass * acceleration, then acceleration =
FORCE / MASS
if force = mass * acceleration, then mass=
FORCE / ACCELERATION
When you fire a gun, the force on the bullet is equal to the _____________
force on the gun
When you fire a gun, the momentum of the bullet just after the shot is fired equals____
the momentum of the gun just after the shot is fired.
why does a bullet go faster forward than the gun moves backwards if they have the same force?
(and they have the same momentum…)
the gun has more mass. If you push a roller skate with the same force that you push a bus, the rollerskate will accelerate faster!
What is a way to think of mass when it comes to moving things?
MASS RESISTS ACCELERATION
(this is what we call inertia, mass is a measurement of inertia)
If you have a force and need to find the X and Y component, how do you do it?
The force given is always the hypotenuse of a right triangle.
Draw an X and a Y component, making a triangle.
The closest (adjacent) side= FORCE * COS (ANGLE) and for the far (opposite) side= FORCE * SIN (ANGLE).
COSINE for CLOSE SIDE
How do you combine forces mathematically?
break the forces down into X and Y components and then combine all the X components and all the Y components into a resultant X and resultant Y. Sketch it. The diagonal of the rectangle made with those is the resultant force and it goes in that direction.
How do you sketch the resultant force of two vectors?
USE THE PARALELLOGRAM RULE.
When you get the resultant X and the resultant Y, how do you find the magnitude of the resultant force?
use pythagorean theorem. R = sqrt (Fx^2 + Fy^2)
When you get the resultant X and the resultant Y, how do you find the direction (angle) of the resultant force?
angle to horizontal = tan-1 (Fy/Fx)
What is momentum?
MASS * VELOCITY
What are two ways to change momentum?
Change the mass or change the velocity
If two objects have the same velocity, the one with the larger mass has _____ momentum
larger
if two objects have the same mass, the one with less velocity has _____ momentum
less
As velocity increases, momemtum _____
increases
What is impulse?
Change in momentum, or FORCE*TIME (a force over an amount of time changes momentum)
What is “FAT MAV?”
F delta T = m delta v
delta (the triangle) means “CHANGE IN”
(force * change in time = mass * change in velocity)