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Question: Can anyone help me with my physics homework?
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I have 3 questions on my physics homework that I need help on. Here they are.
1.The passengers in a roller coaster car feel 50% heavier than their true weight as the car goes through a dip with a 40 radius of curvature.
What is the car’s speed at the bottom of the dip?
2.The ultracentrifuge is an important tool for separating and analyzing proteins in biological research. Because of the enormous centripetal accelerations that can be achieved, the apparatus must be carefully balanced so that each sample is matched by another on the opposite side of the rotor shaft. Failure to do so is a costly mistake. Any difference in mass of the opposing samples will cause a net force in the horizontal plane on the shaft of the rotor. Suppose that a scientist makes a slight error in sample preparation, and one sample has a mass 9.0 greater than the opposing sample.
If the samples are 11 from the axis if the rotor and the ultracentrifuge spins at 7.0×104 , what is the magnitude of the net force on the rotor due to the unbalanced samples?
3.How long will it take a rock dropped from 2.0 above the surface of Mars to reach the ground?
If anyone could explain how to do any or all of these problems, that would be great. Thanks!
“If the samples are 11 from the axis if the rotor and the ultracentrifuge spins at 7.0×104″ should read 7.0 × 10^4.
“If the samples are 11…” should be 11cm and “has a mass 9.0…” should be 9.0mg and “dropped from 2.0…” should be 2m.
Last one I hope! “with a 40 radius of curvature…” should be a 40m radius.
“7.0 × 10^4.” should be 7.0 × 10^4 rpm. This SHOULD be the LAST one!!!!!
ANSWER:
Answer by Seamus O
1. Draw the FBD for it
F(gravitational) = 9.8m Vertically down
F(centripital) = mv²/40 towards center of circle
F(required towards center of circle) = 9.8m + mv²/40 [to keep it in circular motion]
They feel 50%heavier at the bottom of the dip
so F(required) = 1.5 x 9.8m = 14.7m newtons
14.7m = 9.8m + mv²/40
Divide both sides by m:
14.7 = 9.8 + v²/40
4.9 = v²/40
v = √(4.9 x 40)
v = 14 m/s
So the cars speed at the bottom of the dip is 14 m/s
Know better? Leave your own answer in the comments!
