Motion
Speed is a measure of distance covered per unit of this.
Time
Acceleration can be changing when driving at a constant speed if this is changing.
Direction
This is the hang time for most athletes.
less than a second
This is the acceleration during an objects free fall
Gravity
A car moving or a car sitting still will continue to do so due to this.
Inertia
One possible unit of speed is mph which stands for this
miles per hour
Acceleration of a moving object is determined by measuring this and dividing it by time.
Change in speed/velocity
One a basketball player has jumped in the air his acceleration is now this
10 m/s downward gravity (g)
In a vacuum all objects fall at this rate
The same
A car accelerating from a rest at 4 meters per second squared will take this to reach a speed of 80 meters per second
20 seconds
Speedometers measure this type of speed
Instantanteous
Falling objects have this type of acceleration
constant
A ball that has been thrown in the air and reached its peak height has this instantaneous speed
0 m/s
A free falling object falls from a rest for 4 seconds will have about this speed.
40 meters per second
A car travels 5 meter each second for 5 seconds. it has this type of acceleration
constant
Another possible unit for speed is m/s which stands for this
meters per second
Each second an object falls if travels a farther distance than the second before when the object is undergoing this.
Freefall
This is need to describe motion effectively
Frame of Reference
A projectile launched straight up at a velocity of 80 meters per second will take this long to land back on the ground.
16 seconds
Instantaneous speed for a car can be seen on its this
Speedometer
This is motion in relation to a frame of reference
Relative Motion
A ball tossed in the air is always under the acceleration of gravity in this direction
Downward
This is a factor other than gravity that can influence the rate of a free falling ball
air resistance
A free falling object will increase its speed by about this much every second
9.8 m/s
This is what stops a car from moving that is not air resistance
Friction