Half A Second

[jon1968]

I’m trying to explain how close a 100m race is even though on the telly it looks likes there’s a distance between sprinters! There’s sometimes half a second between first and last. It's longer than a blink but....

So, how high off the ground would I have to hold a tin of baked beans (or any other readily available produce) in order to demonstrate how long half a second is between release and impact? Many thanks.

[mibn2cweus]

[wildwood]

Wouldn't the terminal velocity of a full tin of baked beans be faster than an empty one, and so affect the time to fall?

[jim360]

It would affect the time to fall if there were enough distance for the difference in terminal velocities to take effect. Over a short distance there is no meaningful difference between time taken for any two objects.

[jon1968]

Some fabulous answers, thank you! Ended up demonstrating by tapping out the cadence of the opening of ‘Louie Louie’! :-)

[New Judge]

“Take away the air and the two will fall at the same speed, as was demonstrated on the Moon.”

But they didn’t go to the Moon, jim! :

http://www.theanswerbank.co.uk/Science/Question1249555.html

I saw that experiment too. I know… they must have filmed the sequence in a giant vacuum chamber. OR…they could have had the two objects connected to the ground by string and pulleys, Then when they were released a bloke pulled the string to bring them both to the ground at the same speed. OR…the feather could have been made of cast iron and painted white. OR…the ball could really have been a balloon. OR… (that’s enough.. Ed). :-)

[jim360]

Oh, a string! How did I not think of that? :)

[ibannister]

Hi. Any object falling, including your tin of beans, accelerates at 32 ft/sec.
Your tin starts out at zero ft/sec. After 1/2 second it will reach a speed of 16 ft/sec. The average speed would be 8ft/sec.
Therefore, from 4ft it will take 1/2 a second to hit the ground!
Cheers
Ian B.