he bicep curl is an exercise where you lift up a barbell with weights attached by bending your arms at the elbow. Assume your forearm length elbow to hand) is 0.516 m, and the barbell is lifted a vertical distance that is twice the forearm length. Also assume that the barbell is at rest at oth the start and the end of the motion. Calculate how much energy it takes to curl a barbell with a total weight of 72.8 lb? Image size: s ML Max

he bicep curl is an exercise where you lift up a barbell with weights attached by bending your arms at the elbow. Assume your forearm length elbow to hand) is 0.516 m, and the barbell is lifted a vertical distance that is twice the forearm length. Also assume that the barbell is at rest at oth the start and the end of the motion. Calculate how much energy it takes to curl a barbell with a total weight of 72.8 lb? Image size: s ML Max

Physics for Scientists and Engineers: Foundations and Connections

1st Edition

ISBN:9781133939146

Author:Katz, Debora M.

Publisher:Katz, Debora M.

Chapter8: Conservation Of Energy

Section: Chapter Questions

Problem 71PQ: At the start of a basketball game, a referee tosses a basketball straight into the air by giving it...

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The Flybar high-tech pogo stick is advertised as being capable of launching jumpers up to 6 ft. The ad says that the minimum weight of a jumper is 120 lb and the maximum weight is 250 lb. It also says that the pogo stick uses a patented system of elastometric rubber springs that provides up to 1200 lbs of thrust, something common helical spring sticks simply cannot achieve (rubber has 10 times the energy storing capability of steel). a. Use Figure P8.32 to estimate the maximum compression of the pogo sticks spring. Include the uncertainty in your estimate. b. What is the effective spring constant of the elastometric rubber springs? Comment on the claim that rubber has 10 times the energy-storing capability of steel. c. Check the ads claim that the maximum height a jumper can achieve is 6 ft.
At the start of a basketball game, a referee tosses a basketball straight into the air by giving it some initial speed. After being given that speed, the ball reaches a maximum height of 4.25 m above where it started. Using conservation of energy, find a. the balls initial speed and b. the height of the ball when it has a speed of 2.5 m/s.
A block of mass 0.500 kg is pushed against a horizontal spring of negligible mass until the spring is compressed a distance x (Fig. P7.79). The force constant of the spring is 450 N/m. When it is released, the block travels along a frictionless, horizontal surface to point , the bottom of a vertical circular track of radius R = 1.00 m, and continues to move up the track. The blocks speed at the bottom of the track is = 12.0 m/s, and the block experiences an average friction force of 7.00 N while sliding up the track. (a) What is x? (b) If the block were to reach the top of the track, what would be its speed at that point? (c) Does the block actually reach the top of the track, or does it fall off before reaching the top?
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