newton's gravitation

Newton's Universal Law of Gravitation

K Warne

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For FULL presentation click HERE >> www.warnescience.net

49 N

Falling Objects

Two different object with different masses will FALL at the same RATE.

• The force of gravity on 1kg of mass is 9.8 N.

• Each unit of mass has the same force on it!

• Each mass unit will have the SAME ACCELERATION.

1kg5 kg

G10 Revision

1kg

9.8 N

9.8 N

1kg

9.8 N

1kg

9.8 N

1kg

9.8 N

1kg

9.8 N

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Gravitational Field Strength & Acceleration

A gravitational field causes masses inside it to experience a

force of attraction (weight) and therefore accelerate.

g = 9.8 N.kg-1 or m.s-2

Force

g = F/m

Gravitational field

strength

= Gravitational

Force per unit mass

Each kilogram of

mass experiences

9.8 N of force!

Acceleration

g = F/m

Gravitational acceleration

= the rate at which a

falling objects velocity

increases

Falling objects fall 9.8

m.s-1 faster every

second!


http://images.google.co.za/imgres?imgurl=http://www.thinkspace.com/blog/wp-content/uploads/2009/01/earth-transparent.png&imgrefurl=http://www.thinkspace.com/blog/&usg=__ngtYOFoX1seLdVdvYH-T4Utt7rM=&h=390&w=474&sz=192&hl=en&start=2&tbnid=8kfFQsenJm7XzM:&tbnh=106&tbnw=129&prev=/images%3Fq%3Dearth%26gbv%3D2%26hl%3Den



Mass & Weight Examples1. Calculate the weight of a 75 kg person.

2. What would your mass be if you weighed 600 N?

3. What is the mass of an object which weighs 1 N?

4. Calculate the weight of the following:

a) a 500 g tub of margerine

b) 0.2 g of sodium chloride

c) 250 ml of water

d) A 300 mg gold nugget

5. What is the gravitational acceleration on a planet where a 50 kg

object has a mass of 250 N?

6. What is the gravitational field strength if an object weighing 400N

has a mass of 10 kg.

7. If a 4 kg object falls on a planet and gains 30 m.s-1 every 2s then

calculate its weight.SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY




Newton's Universal Law of Gravitation

The force of gravitational attraction that exists between two masses m1 & m2 is given by

d - is the distance of separation between their centres.

m1 m2

d




Relationship between Force, mass and distance.View

this

page as

a slide

show

and the

answers

will be

shown.


re

Fg = G m1∙ m2

r2

Me = mass of the earth

re = distance between centres as

object so small!

Mass of

Object = mo

Fg = G me∙ mo

re2

Fg = mo∙ g (N 2)

But since

mo∙ g = G me∙ mo

re2

g = G me

re2

Gravitational acceleration and Newton


d

Fg is the force of attraction of the earth on the

object AND the attraction of the object on the

earth

ae = Fg

me

Gravitational acceleration and Newton

Fg = G me∙ mo

d2

Fg

ao = Fg

mo

BOTH OBJECTS ACCELERATE TOWARDS EACH OTHER BUT

Since the mass of the earth is much larger the acceleration of the earth

is much smaller!

object

earth

Increasing distance

d (m) Dd 1/Dd 1/(Dd)2 Fg (N)0.01 66.700.02 2 0.5 4 16.680.04 2 0.5 4 4.170.08 2 0.5 4 1.040.16 2 0.5 4 0.260.32 2 0.5 4 0.070.64 2 0.5 4 0.02

10 000 kg

66.7 N66.7 N10 000

kgG 6.67E-11

m1 10000.00 kg

m2 10000.00 kg

d 0.01 m

Fg = G m1 m2

d2

= 6.67E-11 (10000.00)(10000.00)

(0.0001)

=6.67E+01NSAMPLE ONLY SAMPLE ONLY SAMPLE ONLY



Gravitational Field Strength

Calculate the weight of a 5kg bag of sugar on each planet shown.

g = 9.8 N.kg-1 g = 3.8 N.kg-1

A gravitational field causes masses inside it to experience a

force of attraction.

Gravitational field strength = Gravitational Force per unit mass

g = F/m (N.kg-1)

g = 23.6 N.kg-1

5kg5kg

......N......N 5kg

.......N






Mass & Weight Calculate the missing values in each of the

following examples.

OBJECT MASS (kg) WEIGHT

Shoe 0.5

Pen




Newton’s gravitation examples1. Calculate the mass of the earth using the accepted value for g

(9.8 m.s-2) and the radius of the earth 6378.1 km.




Hi -

This is a SAMPLE presentation only.

My FULL presentations, which contain a lot more more slides and other resources, are freely

available on my resource sharing website:

www.warnescience.net(click on link or logo)

Have a look and enjoy!

WarneScience





newton's gravitation

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