12.1 Definitions
Force
a push or pull that acts on an object
What is Static Friction
•is the friction force that acts on objects that are not moving.
the tendency of an object to resist a change in its motion.
•Inertia
•A car with a mass of 1000 kg accelerates. If the net force on the car is 4000 N, what is the car’s acceleration?
4 m/s2
What are the direction and sizes of action and reaction forces?
•These two forces are equal in size and opposite in direction.
Friction
a force that opposes the motion of objects that touch as they move past each other.
Give me an example of Sliding friction
anything that slides
Net force divded by Mass
Acceleration
•A boy pushes forward a cart of groceries with a total mass of 40.0 kg. What is the acceleration of the cart if the net force on the cart is 60.0 N?
1.5 m/s2
What is the momentum Formula?
M = mass x acceleration
•Projectile motion
is the motion of a falling object (projectile) after it is given an initial forward velocity.
Give me an example of rolling friction
Anything that rolls
•Mass
is the amount of matter an object contains.
•What is the upward acceleration of a helicopter with a mass of 5000 kg if a force of 10,000 N acts on it in an upward direction?
2 m/s2
•Calculate the momentum of an object which has a mass of 0.26 kg if it has a velocity of 6.5 m/s.
1.69 Newtons
•Gravity
is a force between any two masses.
What is Fluid friction
opposes the motion of an object through a fluid- liquid or gas.
the force of gravity acting on an object.
-measured in Newtons (N)
•Weight
•An automobile with a mass of 1200 kg accelerates at a rate of 3.0 m/s2. What is the net force acting on the automobile?
3600 Newtons
What vocab term is: if no net force acts on a system, then the total momentum of the system does not change.
•Law of conservation of momentum,
Air resistance
is fluid friction acting on an object moving through the air.
Which way does friction act?
in the direction opposite of motion
Law of Inertia
•The state of motion of an object does not change as long as the net force acting on the object is zero.
•
•A 25-N force accelerates a boy on a skateboard at 0.5 m/s2. What is the mass of the boy and the skateboard?
50 kg
•Which has more momentum, a 46 gram rock with a speed of 30.0 meters per second, or a 8.0-kilogram brick with a speed of 3.0 meters per second?
Brick