Forces Remediation PS.8

Forces Remediation

PS.10​

​What is a force?

Multiple Select

What are two types of forces?

• Newtons

• pulls

• pushes

• an object

​When do objects move?

​Net force= 0 N

Balanced Forces

Unbalanced Forces

​Net force= 100 N

​No movement

Movement

Multiple Choice

Is the Net Force balanced or Unbalanced?

• Balanced

• Unbalanced

Multiple Choice

With unbalanced forces, the object will move in the direction of the _______ force.

• equal

• smaller

• larger

Multiple Choice

If a car has a force of 54 N forwards and the brakes have a force of 73 N backwards, what is the overall Net Force.

• 16 backwards

• 19 backwards

• 18 backwords

• 23 forwards

Multiple Choice

If a person is picking up a book with the force of 50 N and the gravity is pushing down with 15 N, what is the net force?

• 50 N

• 35 N

• 65 N

• 15 N

Force

Newton's 2nd Law of Motion

acceleration of an object is directly proportional to the net force and inversely proportional to its mass. 

²A larger force makes a larger acceleration.

​The relationship between force and acceleration.

³Acceleration is inversely proportional to mass.

For example, this guy easily lifts this little car and knocks it over. But, if we increase the mass and made it a large truck and he used the same force, it wouldn't accelerate as much. This is because acceleration and mass are inversely related.

³Acceleration is inversely proportional to mass.

REMEMBER: as mass increases, so does the object's inertia.

SINCE inertia is an objects resistance to change in velocity...

THEN an increase mass would also resist acceleration.

KEY POINTS!

^1. The net force is what causes acceleration.

^2. If there is no acceleration, the net force must be zero.

^3. If there is acceleration, there must also be a net force.

^4. Force causes acceleration.

^5. Mass resists acceleration.

Multiple Choice

Which grocery basket would have less acceleration?

Multiple Choice

Which grocery basket would have greater acceleration

Multiple Choice

A 20 kg bike accelerates at 10 m/s².  what was the force?

• 25 Newtons

• 20 Newtons

• 200 Newtons

• 10 Newtons

Multiple Choice

If a 2kg bird is pushed by the wind with a force of 2N, how fast does the bird accelerate?

• 1 m

• 2 m/s²

• 4m/s²

• 1 m/s²

What is work?

Multiple Choice

Work is done ___________

• only when force is applied

  on an object

  cause the object to move

  into the opposite direction

  as applied force.

• only when force is applied

  on an object

  cause the object to move

  into the same direction

  as applied force.

Multiple Choice

A mountain climber with a force of 90 N scales a 100 m cliff. How much work is done by the mountain climber?

• 1.11 W

• 9,000 J

• 0.9 J

• 9 W

How POWERFULis she?

When doing a chin-up, Elise lifts her 425 N body
up a distance of 0.25 meters in 2 seconds. What

is the power delivered by her biceps?

W = ?
F = 425 N
d = .25 m
t = 2 s
P = ?

W = Fd

W = (425N)(.25 m)

W = 106.25 Nm

or 106.25 J

P = W/t

P = 106.25 J/ 2 s

P = 53.125 J/s

or 53.125 Watts (W)

Multiple Choice

________________ is the rate at which work is done.

• Power

• Work

• Time

• Energy

Multiple Choice

1. A book weighing 1.0 newton is lifted 2 meters.  How much work was done?

• 2 J

• 0.5 J

Multiple Choice

A young man exerted a force of 9,000 newtons on a stalled car but was unable to move it.  How much work was done?

• 9,000 J

• 0 J= No work

Multiple Choice

You lift a suitcase to put in the overhead luggage compartment of a plane.

• Work

• Not work

Multiple Choice

You throw a baseball a distance of 20 meters.

• Work

• Not Work

Multiple Choice

You push against a brick wall until you are exhausted. The wall does not move.

• Work

• Not work

Multiple Choice

If you have the same work as someone, but in less time

• You are more powerful

• You are less powerful

• You have the same power

Multiple Choice

Person A and Person B are both using the same amount of work to lift something. Person A takes half as much time to do it. Who has greater power.

• Person A

• Person B

Multiple Choice

Which of Newtons laws  best explains why football teams have big, large, fast athletes.

• Gravity

• second law

• first law

• Third law

Multiple Choice

Newton's First Law States........

• Objects at rest tend to stay at rest unless acted on by an outside force.

• Objects accelerate often and it is difficult to know when or how they will accelerate.

• Objects in motion tend to stay in motion unless acted on by an outside force.

• Both A & C

Multiple Choice

What is inertia?

• An object that is accelerating

• Gravitational force

• An objects tendency to stay at rest or in motion

• An unbalanced force

Multiple Choice

Newton's second law states.....

• If there is more mass then there is more acceleration

• An object at rest wants to be in motion

• Force = Mass x Acceleration

• The force exerted on an object is not related to mass or acceleration

Multiple Choice

Newton's third law states.......

• For each action there is a larger reaction associated with it.

• None of these choices

• For each action there is an equal and opposite reaction.

• For each action there is a smaller reaction associated with it.

Multiple Choice

Stacy is rowing a boat. She wants the boat to move forward. According to Newton's Third Law, in which direction should she move her paddle in the water?

• Backwards

• Above her head

• Forward

• East

Multiple Choice

The tendency of an object to just keep doing what it is doing.

• Laziness

• F=MA

• No Clue

• Inertia

Multiple Choice

Which situations show the addition of an external force on an object?

• A child pushes his friend into a swimming pool.

• A family sits on a picnic blanket under a tree.

• A ball rests motionless on the floor.

• A waiter slides tables together for a large dinner party.

Multiple Choice

To travel on his skateboard, Cole uses which of Newton's Laws of Motion?

• 1st

• 2nd

• 3rd

• 4th

Multiple Choice

When a water rocket pushes water out of the nozzle and the rocket is able to travel across the field - What # of Newton's Law is this?

• 1

• 2

• 3

Multiple Choice

A Newton;s cradle is left on your kitchen counter when you leave for school and is still there when you return home. Which of Newton's Laws does ths represent?

• 1

• 2

• 3

Multiple Choice

A garbage can full of trash needs a stronger force to move it to the curb than an empty garbage can. Which of Newton's Laws does this represent?

• 1

• 2

• 3