3 2. What is a net force?The combination of all the forces acting on an objectDetermines whether the velocity of the object will changeAn object accelerates in the direction of the net forceAn object will not accelerate if the net force is zero
4 What are the net forces acting on the following?
5 3. What are balanced forces? Forces that are equal in size and opposite in directionThey combine to produce a net force of zeroNo change in motion occurs (no acceleration)
6 4. What are unbalanced forces? Forces that are unequalThey cause a change in motion (acceleration)Ex: tug of war
7 5. How are forces shown? Using arrows The length of the arrow represents the strength of the forceThe direction of the arrow represents the direction of the force
8 Identify whether balanced or unbalanced forces are responsible for the following different types of movement.A discus thrown through the air.A gymnast balanced on a beam.A sprinter running a bend at a constant speed in a 200 m race.A vehicle traveling along a horizontal linear air trackA car that has a deceleration of 9 m/s2A lift traveling downwards at a constant speed of 1m/s.
9 6. What is friction?A force between two objects in contact that opposes the motion of the objectsIt will cause a moving object to slow down and eventually stopFriction between rough surfaces is greater than friction between smooth surfacesFriction is not always bad – some times we need friction (Ex: to walk, to stop a car)
10 7. What is air resistance?A form of friction caused by air hitting against the surface of a moving object
11 8. What is gravity?The attraction between two particles of matter due to their massGravity is a force
12 9. What is the law of gravitation? It states that all objects in the universe attract each other by the force of gravityThe size of this force of gravity depends on 2 things:The masses of the objects (gravity increases as the masses increases)The distance between the objects (gravity decreases as the distance between the objects increases)
14 1. Who is Isaac Newton?The founder of modern physics
15 2. What is Newton’s 1st law of motion? An object at rest remains at rest and an object in motion remains in motion at a constant velocity unless acted upon by an unbalanced force
16 3. What are some examples of Newton’s 1st law of motion? Riding in a car and slam on brakes and you continue forward
17 4. What is inertia?The tendency of an object to remain at rest or in motion with a constant velocityAll objects have inertia because they resist changes in motion
18 5. What is Newton’s 2nd law of motion? An unbalanced force acting on an object equals the object’s mass times its acceleration.It describes the effect of unbalanced forces acting on an objectThe greater the force, the greater the acceleration if the mass remains constantThe greater the mass, the greater the force needed to accelerate an object
19 6. What is the formula for Newton’s 2nd law of motion? Force = mass x accelerationorF = ma
20 7. What are some examples of Newton’s 2nd law of motion? Pushing an empty grocery cart vs. pushing a full grocery cart
22 10. What is weight?A measure of the force of gravity on an object
23 11. How can F = ma be used to calculate your weight? Weight = mass x gravitational accelerationW = mg
24 12. How are weight and mass different? Mass is a measure of the amount of matter in an objectWeight is a measure of the gravitational force an object experiences due to its mass (so weight depends on gravity)An object’s weight changes when gravity changes but mass always stays the same.
25 14. What is Newton’s 3rd law of motion? (law of action and reaction) for every action force, there is an equal and opposite reaction forceForces always occur in pairsThe action/reaction forces act on different objects
26 15. What are some examples of Newton’s 3rd law of motion? rocketry
27 17. What are 3 types of frictional forces? Sliding friction – occurs when a solid surface slides over another solid surfaceRolling friction – occurs when an object rolls across a solid surface (rolling friction tends to be less than sliding friction)Static friction – occurs between the surfaces of two objects that touch but do not move against each other. To move an object, static friction must be overcome.
28 18. What is a net force?The combination of all the forces acting on an objectIf the net force is zero, no change in movement occurs.