College Physics
1st Edition
ISBN: 9781938168000
Author: Paul Peter Urone, Roger Hinrichs
Publisher: OpenStax College
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Chapter 5, Problem 21PE
A 60-kg and a go-kg skydiver jump from an airplane at an altitude of 6000 m, both falling in the pike position. Make some assumption on their frontal areas and calculate their terminal velocities. How long will it take for each skydiver to reach the ground (assuming the time to reach terminal velocity is small)? Assume all values are accurate to three significant digits.
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A 60-kg and a 90-kg skydiver jump from an airplane at an altitude of 6000 m, both falling in a headfirst position. Make some assumption on their frontal areas and calculate their terminal velocities. How long will it take for each skydiver to reach the ground (assuming the time to reach terminal velocity is small)? Assume all values are accurate to three significant digits.
Terminal velocity is the maximum velocity attainable by an object as it falls through air. Since the drag force of air increases with the increasing falling velocity, the object will reach its terminal velocity during a fall and then remain at that velocity.
Unfortunately, cats fall out of windows in cities sometimes. A famous article, in The New York Times notes that the likelihood that a cat survives a fall goes down as the fall distance increases (expected) but then goes back up at very large distances (perhaps unexpected). If the statistics are correct, then there should be some physical reason this occurs. Some have suggested that terminal velocity and cat biology come into play. The article above indicates that cats have a terminal velocity of 60 miles per hour (mph).
If we model the drag force Fd (N) on a cat as
Fd = 1/2 kAV2
where A is the cross-sectional area of the cat (assuming it is a cylindrical shape), V is its velocity and k=1 kg/m3,
Calculate the cross-sectional…
A basketball player jumps straight up for a ball. To do this, he lowers his body 0.300 m and then accelerates through this distance by forcefully straightening his legs. This player leaves the floor with a vertical velocity sufficient to carry him 0.900 m above the floor. (a) Calculate his velocity when he leaves the floor. (b) Calculate his acceleration while he is straightening his legs. He goes from zero to the velocity found in (a) in a distance of 0.300 m. (c) Calculate the force he exerts on the floor to do this, given that his mass is 110.0 kg.
Chapter 5 Solutions
College Physics
Ch. 5 - Define normal force. What is its relationship to...Ch. 5 - The glue on a piece of tape can exert forces. Can...Ch. 5 - When you learn to drive, you discover that you...Ch. 5 - When you push a piece of chalk across a...Ch. 5 - Athletes such as swimmers and bicyclists wear body...Ch. 5 - Two expressions were used for the drag force...Ch. 5 - As cars travel, oil and gasoline leaks onto the...Ch. 5 - Why can a squirrel jump from a tree branch to the...Ch. 5 - The elastic properties of the arteries are...Ch. 5 - What are you feeling when you feel your pulse?...
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- How would (a) an updraft affect a skydiver in reaching terminal velocity? (b) a downdraft?arrow_forwardThe terminal velocity of a human being is 200 km/hr, and it takes about 12 seconds to achieve this. This calculation considers for air friction of course. What would a person’s speed be if they free fell for 12 seconds instead (no air friction present)?arrow_forwardA basketball player jumps straight up for a ball. To do this, he lowers his body 0.300 m and then accelerates through this distance by forcefully straightening his legs. This player leaves the floor with a vertical velocity sufficient to carry him 0.900 m above the floor. (a) Calculate his velocity when he leaves the floor. (b) Calculate his acceleration while he is straightening his legs. He goes from zero to the velocity found in part (a) in a distance of 0.300 m. (c) Calculate the force he exerts on the floor to do this, given that his mass is 110 kg.arrow_forward
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