Force, Friction, Gravity and Newton s Laws Chapter 3 Lessons 4-6
I can... identify when forces add or subtract. calculate the Net Force. explain the difference between balanced and unbalanced forces.
force: a push or a pull on an object. Newton: unit used to measure force net force: combination of all forces acting on an object friction: force that two surfaces exert on each other when they rub against each other
sliding friction: occurs when solid surface slide over each other static friction: acts between objects that aren't moving; bonds form between non-moving objects and surfaces fluid friction: occurs when a solid object moves through a fluid
rolling friction: occurs when an object rolls over a surface gravity: force that pulls objects toward each other (force of attraction between all objects that have mass) inertia: resistance to changes in motion
Balanced and Unbalanced Forces Balanced forces: forces on object cancel each other out net force is zero object does not change motion object does not accelerate Unbalanced forces: don t cancel out net force is not zero object s motion changes acceleration occurs
An object will speed up, slow down, or turn ONLY if something is applying an unbalanced force to the object. A force is a push or a pull on an object. The unit used to measure force is the Newton (N) Net force: all the forces acting on an object combined The net force determines how the force will affect an object
If the forces are in the same direction, they add together to form the net force. 10 N 10 N 20 N
10 N 10 N If forces are in opposite directions, then the net force is the difference between the forces, and it is in the direction of the larger force.
10 N 15 N 5N If forces are in opposite directions, then the net force is the difference between the forces, and it is in the direction of the larger force.
Forces at different angles partially add and partially cancel each other out 6 N 16 N 8 N 8 N 6 N 10 N
Solve for net force I can. Identify types of friction Explain that gravity depends on mass and distance
Friction force that brings nearly everything to a stop - resists motion changes kinetic energy into thermal Static: bonds form between non-moving objects and surfaces Sliding: slows down objects that are moving (due to roughness of surfaces) Rolling: occurs between ground and the part of the tire touching ground Fluid: occurs when a solid object moves through a fluid
Gravity Force between any two objects that have mass Pulls objects together Depends on the mass of the objects more mass = stronger less mass = weaker Depends on distance farther away = weaker closer = stronger Weight is affect of Earth's gravity upon mass
I can state the two factors that affect gravity explain that gravity affects weight and not your mass summarize Newton s 3 laws of motion use Newton s 2 nd law to solve for force or acceleration
60N
Newton's First Law of Motion (Law of Inertia) An object at rest remains at rest unless an unbalanced force acts on it and causes it to move. A moving object will continue to move in a straight line and at constant speed unless an unbalanced force acts on it and causes it to change. Simplified unbalanced forces are required to cause any acceleration
Newton s 2nd Law connects force, mass, and acceleration. An object acted upon by a force will accelerate in the direction of the force. Net force (N) = mass (kg) Ÿacceleration (m/s 2 ) F net = m Ÿa Acceleration (m/s 2 ) = net force (N) mass (kg) A = F net m
How much force is required to accelerate a 2000kg car at 4 m/s 2 East?
A 2 kg object is pushed with a 10 N forward force, how fast will it accelerate?
Newton's 3rd law: Forces always act in equal and opposite pairs. Action and reaction forces do not cancel out because they act on different objects.
A 500 kg cannon holds a 1 kg cannon ball. When the gunpowder ignites, the explosion provides 1000 N of force in all directions. What is the acceleration of the cannon and cannonball?
I can summarize Newton s 3 laws of motion use Newton s 2 nd law to solve for force or acceleration
What force is required to move a 4000 kg object at an acceleration of 3 m/s 2 North
How much will a 200 kg object accelerate when there is a net force of 40 N South?
If Captain Science's pet magic doggie pushes a 5 kg toy dump truck to the mountain with a force of 100 N Southwest, how fast will the dump truck accelerate?
How much force is required to accelerate a special 120 kg hot air balloon at 4 m/s/s to get Evil Minion's evil cow down to the evil farm?