Physics Study 2 Forces

Question 1

State the definition of inertia:

Answer 1

Resistance to change motion

Question 2

Explain why Newton’s 1st Law is called the “law of inertia”.

Answer 2

Objects in motion want to resist the change in motion. That’s why it takes a force to overcome this resistance.

Question 3

what is the sole factor that determines an objects inertia?

Answer 3

Mass

Question 4

State both definitions of Mass.

Answer 4

Mass is the measure of inertia, it’s how much matter an object contains.

Question 5

state the definition of weight:

Answer 5

Weight is the force due to gravity, changes between planets

Question 6

compare and contrast mass and weight:

Answer 6

Mass is how much matter an object contains and is measured in kilograms (kg) Weight is force (mass * gravity) and is measured in Newtons (N)

Question 7

State Newtons 2nd law of motion.

Answer 7

Acceleration and mass is proportional to the net force acting on the object. £F(net force)=ma. Or acceleration is inversely proportional to the mass of an object £F(net force)/m = a

Question 8

Write the equation form of Newtons 2nd law of motion:

Answer 8

£F(net force) = ma

Question 9

Explain the concepts of direct and inverse proportionality.

Answer 9

Direct: if one variable increases, the other variable increases or if one variable decreases the other variable decreases.
Inverse: if one variable increase, the other variable decreases or if one variable decreases the other variable increases.

Question 10

State the definition of force:

Answer 10

a push of pull

Question 11

what is the unit of force? how is this unit mathematically derived?

Answer 11

(N) = kg*m/s2

Question 12

state the definition of net force:

Answer 12

the total forces acting on an object, shown with a sigma. £F(net force)

Question 13

If a 50 N force is applied to the right of an object, and a 30 N force is applied to the left on the object, what is the net force acting on the object?

Answer 13

50N-30N = 20 N

Question 14

explain the difference between a vector quantity and a scalar quantity.

Answer 14

Vector= magnitude and direction
Scalar = just magnitude

Question 15

state the definition of equilibrium:

Answer 15

The object or system is balanced, moving at constant velocity and £F(net force) = 0

Question 16

what is a balanced force? what is an unbalanced force?

Answer 16

balanced = equilibrium, moving at constant velocity £F(net force) = 0
unbalanced = not in equilibrium acceleration, vel £F(net force) = ma

Question 17

state the definition of normal force:

Answer 17

Surface/ground reaction, force, perpendicular to the surface

Question 18

State the definition of tension force:

Answer 18

A pulling force on a cable, string, rope etc

Question 19

State the definition of friction force:

Answer 19

Resistance force which opposes motion.

Question 20

provide a basic explanation of what causes friction at the molecular level:

Answer 20

Surfaces are not smooth, and it’s this roughness that causes friction

Question 21

State Newton’s 3rd law of motion:

Answer 21

For every action is an equal and opposite reaction

Question 22

Describe the relationship between an action and a reaction force

Answer 22

A action causes an reaction force. EX: a hammer (the action) hits a nail which pushes back on the hammer (the reaction)

Question 23

State Newtons 1st Law of motion:

Answer 23

An Object in motion will move at constant velocity unless acted upon by and unbalanced force. £F=0