AP Physics 1

 

Invisible Flame

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E. Solving Problems using the motion equations

 

 

 

 

Ex 3) Starting from rest, an object accelerates at a rate of 12 m/s2. What is the velocity of the object at the end of 3 seconds?

 

Vi = 0 (Starting from rest)

a = 12 m/s2

Vf = ?

t = 3.0 seconds

 

a = (Vf - Vi)/t

 

12 m/s2 = (Vf - 0)/3.0 secs

(Cross Multiply and Solve)

 


Vf = 36 m/s

 

 

 

Ex 4) An object at 100. m/s accelerates at a rate of 120. m/s2. What will the velocity of this object be after .100 seconds?

 

a = (Vf - Vi)/t

 

120. m/s= (Vf - 100. m/s)/.100 s

 

• Cross Multiply

 

12.0 = (Vf - 100.)

 

 

Vf = 112 m/s

 

 


3 ways to have non-zero acceleration

 

 

(to change velocity):

 

Speed Up

• Slow Down

 

• Change Direction

 

 

F. Motion Terms and Direction

A whole branch of mathematics is required to deal with numbers that have direction

 

Trigonometry


This is why it is important to know which motion information has direction

 

Vector - a quantity that includes magnitude (a number) & direction

 

ex) displacement, acceleration, velocity

 

 

Scalar - a quantity that includes magnitude (a number) only

 

 

ex. time, distance, speed

 

 

 

 

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