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When is the acceleration negative? positive?

What would happen if this bottle were dropped?

 

 

Newton's Masterpiece!

Sir Isaac Newton's own first edition copy of his Philosophiae Naturalis Principia Mathematica
with his handwritten corrections for the second edition.

The first edition was published under the imprint of Samuel Pepys who was president of the Royal Society. By the time of the second edition, Newton himself had become president of the Royal Society, as noted in his corrections.

The book can be seen in the Wren Library of Trinity College, Cambridge.

Photograph © Andrew Dunn,
5 November 2004.
www.andrewdunnphoto.com/

 

 

 

4. Standard Equation

       

Fnet = ma
(N)  (Kg)(m/s2)

   

Newton - force needed to give a 1 kg of mass an acceleration of 1 m/s2

 

Derived unit - A unit that comes from the combination of other units

 

N = Kgm/s2

 

Fundamental unit
(opposite) m, s, Kg

 

 

 

 

Force Questions

 

 

Ex 1) What is the net force necessary to give a 3.0 kg mass, initially at rest, an acceleration of 5.0 m/s2?

 

 

 

 

Ex 1) What is the force necessary to give a 3.0 kg mass, initially at rest, an acceleration of 5.0 m/s2?

 

F = ma

(3.0 kg)(5.0 m/s2)

= 15 N

 

or

 

 15 kgm/s2

 

 

 

Ex 2) A net force of 30. nt accelerates an object by 15. m/s2.

Find the objects mass..

 

Ex 2) A force of 30. nt accelerates an object by 15. m/s2.

 

Find the objects mass.

 

 

F = ma

 

30. N = m (15. m/s2)

 

 

m = 2.0 kg

 

 

 

 

Ex 3) An unbalanced force of 100. nt acts on a 50. kg mass for 5.0 seconds. 

 

Find the acceleration of the mass.

 

 

 

Ex 3) An unbalanced force of 100. nt acts on a 50. kg mass for 5.0 seconds. 

Find the acceleration of the mass

 

Fnet = ma

 

 

 

100. nt = (50. kg) a

 

 

 

a = 2.0 m/s2

 

 

 

 

Ex 4) A 10. kg cart moving with a velocity of 2.0 m/s is brought to a stop in 2.0 sec. 

Find magnitude of the average force used to stop the cart.

 

 

Ex 4) A 10. kg cart moving with a velocity of 2.0 m/s is brought to a stop in 2.0 sec. 

Find magnitude of the average force used to the stop cart.
                  

 

m = 10. kg

t = 2.0 sec

Vi = 2.0 m/s

Vf = 0 m/s

(stop)

F = ?

 

 

F = ma

 

 

a = ?

 

 

a = Vf  - Vi = 0 - 2.0 m/s
t  2.0 sec

 

 

a = -1.0 m/s2
         


Fnet = ma

 

= (10. kg)(-1.0 m/s2)

 

= -10. N

or

 -10. kg•m/s2

 

 

 

 

Ex 5) The object below has a mass of 5 kg.

Find its acceleration.

 

 

 

Fnet = ma

 

 

 

40 N East = (5 kg)a

 

 

 

a = 8 m/s2 East

 

 

 

 

 

Ex 6) The block above has an acceleration of 22. m/s2.

What is the mass of the block?


5N2 + 10N2 = R2

Fnet = ma

Fnet=11 N=m(22 m/s2)

 

m = .50 kg 

 

 

 

 

 

Ex 7) If the magnitude
of the block’s acceleration is 2.0 m/s2, what is the mass of the block?

 

 

Fnet = ma

 

10 N Left = m(2 m/s2)

 

m = 5 kg

 

 

 

 

 

 

What will the balloon do

when the cart is pushed

to the left?

 

(Click on image)

Rutgers U

Balloon_in_car

 

 

 

 

 

 

 The air in the container
tends to remain at rest. When the cart is pushed
to left, air pressure
builds up on the right
side of the container. 

 

 

Try this at home!

 

 

 

Ranking Task


Rank the acceleration
 from least to greatest.

leastAccel

Rank the accelerations
from least to greatest

Fma1

Fma2

 

 

 

3rd Law
 Of Motion

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