Physics Class 1: Motion

formula for average speed

the distance divided by the time of travel, s=d/t

what time goes up, what does down?

the speed

instantaneous speed

the rate at which distance is covered at any given time

how is instantaneous speed found

by computing average speed for a very short interval of time

velocity

speed AND direction

vector

anything where size and direction matters, shows direction of magnitude

acceleration

the rate at which velocity changes

formula for acceleration

a=Δv/t or acceleration=change in velocity/elapsed time

formula for calculating distance

d=(1/2)at²

formula for calculating distance if the object was already in motion

d=v₀t + (1/2)at²

what does gravity cause

acceleration

since gravity causes acceleration, what will happen to velocity?

velocity will continue to increase at a steady rate

since gravity causes acceleration, what will happen to speed?

speed will increase at an exponential rate

significant figures

whenever you’re adding multiplying, or dividing number’s together, you cannot use more than the number of digits of the smallest number in expressing the answer

what is the (non-approximate) gravitational acceleration?

g=9.8m/s²

what is the approximate gravitational acceleration?

10m/s²

to calculate, if someone is throwing a ball upward, what do we need to know?

we need to know with what velocity he is throwing the ball

trajectory

when something moves forward against gravity

for trajectory, how is velocity calculated?

by adding the vertical component of velocity to the horizontal component of velocity

for calculating velocity values in gravity tables and stuff, the formula is

v=v₀ + at

we add the change in velocity (at) to the initial velocity (v₀)

for calculating distance values in gravity tables and stuff, the formula is

d=v₀t + (1/2)at²

(v₀t) is the distance the ball would travel if it continued to move with just it’s original velocity

(1/2)at² is due to acceleration