1.2 Forces And Newton’s Laws

Question 1

In physics a ______ is a measurable influence that causes something to move

Answer 1

Force

Question 2

Newton’s first law?

Answer 2

Any object continues at rest or at constant velocity unless an external force acts on it!

Question 3

External forces give objects acceleration. The acceleration is proportional to the force applied, and the constant of proportionality is the

Answer 3

Mass (meaning the more mass a force has the more acceleration it will give)

Question 4

Newtons 2nd Law?

Answer 4

F=ma, The greater the mass of an object the more force it will take to accelerate that object

Question 5

What is the Si unit of a force

Answer 5

Newton (N)

Question 6

Any object of mass m falls with an acceleration off (9.81) downward, meaning it must be acted on by a force, this downward force due by the gravitational attraction between earth and the object is called the objects..?

Answer 6

Weight
Direction: down toward the centre of the earth
W=mg, therefore the weight of an object is a force not a mass

Question 7

A force that only acts on objects at rest is called the

Answer 7

an upward force called the contact force cause objects are in contact like a statue and a table, when a contact force acts perpendicular to the surface we call it the NORMAL FORCE (FN)

Question 8

Newtons 3rd law?

Answer 8

Forces come in pairs, for every action there is an equal and opposite reaction. For every force applied to a body there is a force applied by that body.

Question 9

When an object A exerts a force on B and B exerts a force equal in size but inn opposite direction on A this vans be referred to as Newtons ___ law

Answer 9

3rd

Question 10

The force applied by one body A on another object B is known as the

Answer 10

Action

Question 11

The second force B responding to the force exerted by Object A is known as the

Answer 11

Reaction

Question 12

Action and reaction forces act on

Answer 12

Different objects

Question 13

Not action and reaction forces

Answer 13

Action and reaction forces

Question 14

List the 4 fundamental forces

Answer 14

1. Electromagnetic force
2. Gravitational force
3. Strong nuclear forces
4. Weak nuclear forces

Question 15

List the 3 derived forces

Answer 15

1. Normal force
2. Tension force
3. Friction force

Question 16

What force do we see when pulling on a rope

Answer 16

Tension force

Question 17

There is a ball hanging by a string, gravitational force acting down on it so why doesn’t it fall?

Answer 17

Because of the tension force acting alone the string keeping it up.

Question 18

Any force that appears as a result of pulling on a rope, a string or anything similar is a

Answer 18

Tension force

Question 19

Tension forces are opposite to

Answer 19

Normal forces

Question 20

General info

Answer 20

Instead of resisting compression like normal forces, tension forces resist forces that cause things to stretch. When we hang a ball on a rope the rope applies a force to the ball which makes it resist being stretch out out, the result is tension.

Question 21

How are tension and normal forces opposite to each other

Answer 21

When an object is not pushing against a surface the Normal force= 0
When an object is not pulling on a rope the Tension force= 0

Question 22

If a ball hanging from a rope has a mass of 10kg, what is the tension force

Answer 22

98.1 N (up)

• we look at the forces acting on the ball= gravity (downward) and the tension force (pulling upward) being applied by the rope onto the ball.
• we see the ball isn’t moving so the forces must cancel out.
• we have to find force of gravity, Fg
  Fg=ma, m=10, a=9.81 m/s^2 (down)
  = 98.1 N (down) for the weight of the ball
• since the gravitational force must be cancelled by the tension on the rope, Fg=Ft, hence Ft is 98.1 N (up)

Question 23

The ____ force is directed away from the body/ball along the cord

Answer 23

Tension

Question 24

The cable in tension forces is assumed to be

Answer 24

Massless and unstretchable

Question 25

The resistance we get by a bonding between a body we’re trying to push and its surface is known as a

Answer 25

Friction force

Question 26

The friction force is directed along the surface, _______ to the direction of the intended motion

Answer 26

Opposite

Question 27

When we see the word (motion) the resistance is ______friction (object is moving)

Answer 27

Kinetic

Question 28

When we see the word (tends to move) the resistance is ______friction (object at rest while pushing/not moving)

Answer 28

Static

Question 29

To find static and kinetic friction we use the same rule

Answer 29

F= uN

Question 30

The coefficient of kinetic friction is always smaller than the static friction, why?

Answer 30

Because static friction is motionless, meaning moire friction = larger coefficient of friction

Question 31

Is force vector or scalar

Answer 31

Vector

Question 32

The weight of an object is a force?

Answer 32

True, weight should be measured in Newtons even

Question 33

The acceleration of a body ______ on the applied force

Answer 33

Depends

Question 34

In the phrase normal force what does normal mean?

Answer 34

The force exerted by a surface that is PERPENDICULAR to the surface (perpendicular must be in the sentence)

Question 35

A lizard (mass m) basks in the sun on a sloping rock, the net force is

Answer 35

Zero

Question 36

What is the force required to accelerate a mass of 10.0 kg at 4.00 m/s^2

Answer 36

F=ma, 10(4) = 40 N