Newton’s First & Second Laws of MotionChp 12.2 Pg 363-369

Newton’s First & Second Laws of MotionChp 12.2 Pg 363-369

Newton’s First Law of MotionNewton’s First Law of Motion

According to the 1st Law of motion, the state of motion of an object does not change as long as the net force on the object is zero Unless an unbalanced force acts, an object at rest will remain at rest and an object in motion will remain in motion at constant velocity

According to the 1st Law of motion, the state of motion of an object does not change as long as the net force on the object is zero Unless an unbalanced force acts, an object at rest will remain at rest and an object in motion will remain in motion at constant velocity

InertiaInertia Newton’s 1st Law is known as the Law of Inertia

Inertia is the tendency of an object to resist change in its motion. An object at rest stays at rest and an object in motion stays in motion at constant velocity

Newton’s 1st Law is known as the Law of Inertia

Inertia is the tendency of an object to resist change in its motion. An object at rest stays at rest and an object in motion stays in motion at constant velocity

QuickTime™ and a decompressor

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are needed to see this picture.The coin stays in place above the cup, then falls

The coin wants to stay at rest

Inertia continuedInertia continued

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The man wants to stay in motion. So he continues moving The man wants to stay in motion. So he continues moving forward at constant velocity. However, gravity begins to act forward at constant velocity. However, gravity begins to act on him while he is airborne and eventually he will fall to the on him while he is airborne and eventually he will fall to the groundground

Inertia and Car AccidentsInertia and Car Accidents

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Wear your seatbelt!!!!!Wear your seatbelt!!!!!

Head keeps moving

Newton’s Second LawNewton’s Second Law

Mass is a measure of the inertia of an object that depends on the amount of matter the object contains. (an amount of matter)

Acceleration of an object is equal to the net force acting on it divided by the object’s mass

Mass is a measure of the inertia of an object that depends on the amount of matter the object contains. (an amount of matter)

Acceleration of an object is equal to the net force acting on it divided by the object’s mass

2nd Law Formula variations and units2nd Law Formula variations and units

Force = mass x acceleration F = m x a units = Kg x m/s2 = Kgm/s2 = N

Acceleration = Net force Mass

a = _F_ units = N or Kgm/s2 = m/s2

m Kg Kg

Mass = force acceleration

M = F units = N or Kgm/s2 = Kg

a m/s2 m/s2

Force = mass x acceleration F = m x a units = Kg x m/s2 = Kgm/s2 = N

Acceleration = Net force Mass

a = _F_ units = N or Kgm/s2 = m/s2

m Kg Kg

Mass = force acceleration

M = F units = N or Kgm/s2 = Kg

a m/s2 m/s2

A car with a mass of 1200 kg accelerates at a rate of 2 m/s2 in the forward direction. What is the net force acting on the car?

A car with a mass of 1200 kg accelerates at a rate of 2 m/s2 in the forward direction. What is the net force acting on the car?

Given info: m = 1200 kg a = 2 m/s2

Step 1 Step 2 Step 3

F = m x a F = 1200 kg x 2 m/s2 F = 2400 kgm/s2

or 2400 N

Given info: m = 1200 kg a = 2 m/s2

Step 1 Step 2 Step 3

F = m x a F = 1200 kg x 2 m/s2 F = 2400 kgm/s2

or 2400 N

Given info: m = 1000 kg F = 2000N

Step 1 Step 2 Step 3

a = F a = 2000 N kgm/s2 a = 2 m/s2

m 1000 kg

Given info: m = 1000 kg F = 2000N

Step 1 Step 2 Step 3

a = F a = 2000 N kgm/s2 a = 2 m/s2

m 1000 kg

A car with a mass of 1000 kg accelerates when the light turns green. If the net force on the car is 2000 N what is the car’s acceleration?

A car with a mass of 1000 kg accelerates when the light turns green. If the net force on the car is 2000 N what is the car’s acceleration?

A 30 N force accelerates a boy on a skateboard at 0.5 m/s2. What is the mass of the boy and skateboard?

A 30 N force accelerates a boy on a skateboard at 0.5 m/s2. What is the mass of the boy and skateboard?

Given info: a = 0.5 m/s2

F = 30 N

Step 1 Step 2 Step 3

m = F m = 30 N kgm/s2 m = 60 kg

a 0.5 m/ss

Given info: a = 0.5 m/s2

F = 30 N

Step 1 Step 2 Step 3

m = F m = 30 N kgm/s2 m = 60 kg

a 0.5 m/ss

Weight and Mass Weight and Mass Weight is the force of gravity acting on an object. It is the product of the object’s mass and acceleration due to gravity acting on it. Mass and weight are not the same. The unit for mass is kg and unit for weight is N

Mass is the measure of inertia on an object (an amount of matter); weight is a measure of the force of gravity acting on an object

Weight is the force of gravity acting on an object. It is the product of the object’s mass and acceleration due to gravity acting on it. Mass and weight are not the same. The unit for mass is kg and unit for weight is N

Mass is the measure of inertia on an object (an amount of matter); weight is a measure of the force of gravity acting on an object

Weight problemsWeight problems Weight = mass x acceleration due to gravity

w = m x g Units = kg x m/s2 = kgm/s2 = N

What is the weight of a man if his mass is 112 kg and gravity is 9.8m/s2?

w = m x g w = 112 kg x 9.8 m/s2

w = 1100 kgm/s2 or 1100N

Weight = mass x acceleration due to gravity

w = m x g Units = kg x m/s2 = kgm/s2 = N

What is the weight of a man if his mass is 112 kg and gravity is 9.8m/s2?

w = m x g w = 112 kg x 9.8 m/s2

w = 1100 kgm/s2 or 1100N

Weight changes if gravity changesWeight changes if gravity changes

If gravity the moon is 1/6 that of Earth’s gravity the weight of a 60 N rock on Earth will only be 10 N on the moon.

What would the weight of a dog be on the moon if its weight on earth is 54 N? 54 N x 1 = 9 N 6

No matter the gravity, mass is always the same

If gravity the moon is 1/6 that of Earth’s gravity the weight of a 60 N rock on Earth will only be 10 N on the moon.

What would the weight of a dog be on the moon if its weight on earth is 54 N? 54 N x 1 = 9 N 6

No matter the gravity, mass is always the same

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