Free Fall
Free fall motion is...
Falling caused by gravity, with nothing else effecting it (no air resistance)
An object moving upward in the air is ___________ because gravity is pulling in the opposite direction.
Slowing down!
An object is released from very high up. After 2 seconds how fast is it going?
v = 19.6m/s
A rock is tossed upwards at 40 m/s. How long does it take to reach its highest point?
t = 4.08 s
In real life objects, do they use "free fall" motion? Stick to the definition.
No! In real life we always deal with air, which we ignore for free fall motion.
At the very top of upward motion, what does the object do as it changes from moving upward to moving downward?
It stops!
A ball is dropped from a lab table. How far will it travel in 0.3s?
d = 0.441m
A rock is tossed upward with a velocity of 40 m/s. How high does it go?
y = 81.63 m
What is the acceleration of objects free falling?
9.8 m/s2 , negative going up and positive going down.
Upward motion is symmetrical. Explain what that means.
It means: distance traveled up = distance traveled down, time to get to the top = time to get back down, speed at a given height going up = speed at same height going down
A physics marble falls a distance of 1.2 meters. How long did it take to hit the ground?
t = 0.35 s
A bow is fired straight into the air with a velocity of 51 m/s. How long does it take to hit the ground?
time up = 5.204s time down = 5.204s because it is SYMMETRICAL total time is 10.408 s
Object A has a mass of 10kg Object B has a mass of 50kg. If we drop both A and B from the same height at the same time, which will hit the ground first?
They will hit the ground at the same time because the acceleration due to gravity (little g) does not change when mass changes.
The first half of upward motion has a positive ___________ and a negative ____________
Initial velocity, acceleration (gravity)
A falling pastry hits the ground with a velocity of 23 m/s. How long was it falling?
t = 2.35s
When a rocket is launched it has an initial velocity of 131 m/s. How fast is it going when it returns to Earth?
131 m/s because upward motion is SYMMETRICAL.
Object A has a mass of 10kg Object B has a mass of 50kg If both A and B roll off a table with the same speed, which will hit the ground farther from the table.
They will hit at the same distance. Because both objects A and B will fall at the same rate they will be in the air for the same amount of time. They are also going the same speed, so they will cover the same amount of distance in the time before they hit the ground.
Once the object has reached its peak (highest it can travel) we can consider the acceleration to be ____________ until it hits the ground.
positive
A falling chunk of ice smashes into the ground with a velocity of 18 m/s. How high did it fall from?
The height it fell FROM is 16.53 m
A student bouncing on a trampoline is bounced upward at 11.3 m/s. How high does the student go? How long is the student in the air?
y = 6.514m
Time in air = time up + time down = 1.153s + 1.153s = 2.306s