Now that we have the concept of acceleration, we can use it to do more than simply tell how fast something’s velocity changes. This time, we take a look at how fast something’s falling based on how much time’s passed since it started falling, but first there’re a couple things you shold know.
The higher an object’s cross-sectional area to mass ratio, the lower its terminal velocity. What that means is that if you have a pencil (something that weighs a lot for the area air hits), it can fall faster than a parachute (something that has a lot of area for the air to hit compared to its weight).
The higher an object’s cross-sectional area to mass ratio, the lower its terminal velocity. What that means is that if you have a pencil (something that weighs a lot for the area air hits), it can fall faster than a parachute (something that has a lot of area for the air to hit compared to its weight).
g=-9.8m/s2
The gravitational acceleration near Earth’s surface is about -9.8m/s2, meaning that things accelerate by 9.8m/s2 toward the ground when they fall. Next, we need a formula.
v=v0+at
v is the velocity when you finish measuring it. v0 is the velocity when you started. Today, we’ll simply let go of the object, so we can ignore that part. a is the acceleration, and t is the amount of time that passed. Great, now we can calculate something. Say I were to stand on top of a tall building, let go of a ball over the street, and hope there weren’t any people down there. How fast would it be going after 5 seconds? (It’s always a good idea to put your units just to make sure nothing gets messed up.)
v=0m/s+(-9.8m/s2•5s)
↓
v=-9.8•5ms/s2
↓
v=-49m/s
↓
v=-9.8•5ms/s2
↓
v=-49m/s
Remember a negative is either left, back, or down. The ball has a velocity of 49m/s down 5 seconds after being let go. I sure hope no one was down there or I’m going to jail.
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