Chapter 4

Question 1

Study of dynamics

Answer 1

The explanation of motion in terms of the forces that act on an object.
*pg74

Question 2

Push

Answer 2

A push or pull exerted by one object on another.

*pg74

Question 3

Different types of forces:

tension; gravitational force; air resistance; normal force; fictional force; electrostatic force

Answer 3

• • tension: If you pull on a rope attached to a crate
• • gravitational force: the force of gravity when something/someone is falling down
• -air resistance: the upward force exerted by the air when something/someone is falling down
• -normal force: the force exerted by the floor when something/someone is standing, or by the table if something is on it, and etc
• -Frictional force: when you slide something against the floor/table, they exert frictional force on the item
• • electrostatic force: an example is static cling (all of these forces except gravitational are examples of electromagnetic force)
• pg74

Question 4

Newton’s first law

Answer 4

AKA law of inertia. If the object is at rest, it will remain at rest, and if the object is moving, then it will continue to move with constant velocity unless something changes that by adding a force
no net force = no acceleration
*pg74

Question 5

Inertia

Answer 5

an object’s natural resistance to change in their state of motion.
*pg74

Question 6

mass

Answer 6

The quantitative measure of its inertia. It measure how much matter is contained in an object. Measured in Kg. Different than weight.
*pg74

Question 7

Newton’s second law

Answer 7

If F_net is the net (total) force acting on an object of mass, m, then resulting acceleration of the object, a, satisfies the simple equation:
F_net = ma
note: any force exerted by the object is not included in F_net, only forces exerted on the objects.
*pg75

Question 8

Newton’s third law

Answer 8

If object 1 exerts a force on object 2, then object 2 will exert a force back on object 1. They will have the same magnitude but act in opposite directions. They are said to form an action-reaction pair.
*pg76

Question 9

weight vs mass

Answer 9

Weight is the gravitational force exerted on it by earth or whatever planet, and mass is an intrinsic property and does not change with location.
weight = mg
*pg80

Question 10

Newton’s law of gravitation

Answer 10

Every object in the univerese exerts a gravitational pull on every other object. The magnitude of this gravitational force os proportional to the product of the objects’ masses and inversely proportional to the square of the distance bw them.
F_grav = G Mm/r^2 (value of G = 6.7x10^-11 Nm2/Kg2 ) no need to memorize this number
*pg81

Question 11

Equation to find gravitational acceleration

Answer 11

g = G M/r2

*pg82

Question 12

Static and kinetic friction

Answer 12

Static is when theres no relative motion bw the surfaces that are in contact (no sliding)
kinetic is the opposite (sliding does occur)
*pg84