Word Problems (AP) - Kinematics | Show Me The Physics

Enrichment: Invisible Flame

Relight a Candle from Afar

E. Solving Problems Using the Motion Equations

Ex 3

Given

Starting from rest, an object accelerates at a rate of 12 m/s².
Find: the velocity of the object at the end of 3.0 seconds.

↓

V_i = 0 a = 12 m/s² t = 3.0 sec

a = (V_f − V_i)/t →
12 m/s² = (V_f − 0)/3.0 sec

V_f = 36 m/s

Ex 4

Given

An object at 100. m/s accelerates at a rate of 120. m/s².
Find: the velocity of this object after .100 seconds.

↓

a = (V_f − V_i)/t →
120. m/s² = (V_f − 100. m/s)/.100 s

Cross Multiply: 12.0 = (V_f − 100.)

V_f = 112 m/s

3 Ways to Have Non-Zero Acceleration

(to change velocity)

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