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# L2 Forces, Mass, Acceleration, Pressure, Review of Exponents - PowerPoint PPT Presentation

L2 Forces, Mass, Acceleration, Pressure, Review of Exponents. Frictionless motion Demo. 5.NEWTON’S FIRST LAW OF MOTION. Newton finished the overthrow of Aristotelian ideas. Law 1 (Law of Inertia)

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L2 Forces, Mass, Acceleration, Pressure, Review of Exponents

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### Frictionless motionDemo

5.NEWTON’S FIRST LAW OF MOTION

Newton finished the overthrow of Aristotelian ideas.

Law 1 (Law of Inertia)

Every object continues in its state of rest, or of uniform motion in a straight line, unless it is compelled to change that state by forces impressed upon it.

“If you leave an object alone, it has constant velocity.”

### Newton's concept of motion said that the natural state of an object was

(a) constant velocity

(b) constant acceleration

(c) constant net force

### We call the change in velocity per unit time the accelerationa= Δv/ ΔtThe Δv can be in magnitude and/or direction

The combination of forces that act on an object is the net force.

(Only the net force is shown in the figures on this slide.)

m

m

m

This symbol means

proportional to

### FORCE CAUSES ACCELERATION

F

a

F

a

F

a

The acceleration of an object is directly proportional to the net force.

5. NEWTON’S SECOND LAW OF MOTION

• The force in each of these equations represents the vector sum of all of the forces acting on the object of mass m.

• Units of force - N and lb

or

slug)

A slug weighs

Every object possesses inertia (mass).

Inertia is the sluggishness of an object to changes in its state of motion.

Mass - a measure of the inertia of an object

(Units - kg and

### 3.MASS AND WEIGHT

32 lb.

• Inertia deals with how hard it is to start and stop an object.

m1

m2

r

### 2.The Universal Gravitational Constant, G

At earth’s surface,F = G mMe/Re2 orW = (Gme/Re2) m or W=(g)m orweight = mass x acceleration of gravityg = 9.8 m/s2

### 2 Concepts of Mass: Equivalence of gravitational mass and Inertial massTheory of General relativity

Pressure=Force/contact areaOn left, the pressure on the bottom block, i.e. the weight of the top block/contact area, is lower than the pressure on the bottom block on the right.

### Exponential Notation

1000 = 10 x 10 x 10 = 103

100 = 10 x 10 = 102

10 = 101

1 = 100

0.1 = 1/10 = 10-1

0.01 = 1/100 = 10-2

0.001 = 1/1000 = 10-3