I need help with question 8.2? 8.1. A meter stick balances on a knife edge be-low the 50 cm mark. When two nickels arestacked and centered on the 12 cm mark, thewhole system is now found to balance whensupported at the 45 cm mark. If a nickel hasa mass of 5.0 g, what is the mass of the meterstick?8.2. A metal bar hangs loosely from a pivot on the ceiling. A parentpushes on the bar with a force F₁ horizontally at a distanceY₁ = 0.6 m below the ceiling. Their child pushes near the bottomof the bar in the opposite direction, applying a force F235 Nat a point y₁ = 1.1 m below where their parent is pushing.(a) How hard does the parent have to push to keep the barfrom moving?(b) What is the magnitude and direction of the net force onthe pivot point if the mass of the bar is 1.8 kg?F₂Y1Y2F₁8.3. A diver has a mass of 70 kg. In 'tuck' position, we can treat this mass as a disc of radius0.50 m, but when fully extended, the diver is more like a rod of length 2.4 m.8.4. The bicep muscle pulls on the bones of the forearm at a fairlyshort distance from the elbow, which acts as a pivot point. Anobject is held motionless in the hand at an angle60° tothe bicep which is aligned vertically, as shown in the figure tothe right. The bicep must exert a force to keep everything inequilibrium.(a) Compare the rotational inertia of this diver in tuck position to their rotational inertiawhen fully extended.(b) If this diver ends their dive fully extended and is rotating at 0.85 rotations/s, what wastheir rotational speed earlier in the dive when they were in tuck position?(c) Does the transition from tuck to fully extended require extra energy to be provided bythe diver's muscles?(a) What torque does a 5.0 kg object create relative to the elbow if the distance from theelbow to the center of the hand is 35.0 cm?(b) If the forearm itself has a mass of 2.0 kg and a center of mass that is 16 cm from theelbow, what torque does that create relative to the elbow?(c) What force must the bicep exert to keep things in equilibrium if the distance from theelbow to the point of attachment for the bicep is 4.0 cm along the forearm?(d) What is the magnitude of the force of compression in the elbow joint?

Answered: Image /qna-images/answer/8b2d9385-7359-4041-aa28-46a47f952345.jpg

8.2. A metal bar hangs loosely from a pivot on the ceiling. A parent pushes on the bar with a force F₁ horizontally at a distance y₁ = 0.6 m below the ceiling. Their child pushes near the bottom of the bar in the opposite direction, applying a force F₂ = 35 N at a point y₁ = 1.1 m below where their parent is pushing. (a) How hard does the parent have to push to keep the bar from moving? (b) What is the magnitude and direction of the net force on the pivot point if the mass of the bar is 1.8 kg? F2 Y1 Y2 F₁

8.2. A metal bar hangs loosely from a pivot on the ceiling. A parent pushes on the bar with a force F₁ horizontally at a distance y₁ = 0.6 m below the ceiling. Their child pushes near the bottom of the bar in the opposite direction, applying a force F₂ = 35 N at a point y₁ = 1.1 m below where their parent is pushing. (a) How hard does the parent have to push to keep the bar from moving? (b) What is the magnitude and direction of the net force on the pivot point if the mass of the bar is 1.8 kg? F2 Y1 Y2 F₁

Glencoe Physics: Principles and Problems, Student Edition

1st Edition

ISBN:9780078807213

Author:Paul W. Zitzewitz

Publisher:Paul W. Zitzewitz

Chapter9: Momentum And Its Conservation

Section: Chapter Questions

Problem 1STP

See similar textbooks

Similar questions

In order to balance a meterstick at the 27 cm mark, how much weight would you need to hang at the 10 cm mark? Assume the stick weighs 200 g and its center of mass is at 50 cm.
Find the x- and y -coordinates of the center of gravity for theboomerang in Figure P8.12a, modeling the boomerang as inFigure P8.12b, where each uniform leg of the model has alength of 0.300 m and a mass of 0.250 kg. (Note: Treat the legslike thin rods.)
A bowling ball rolls up a ramp 0.8 m high without slipping. It has an initial velocity of its center of mass of 4.2 m/s. What is its velocity at the top of the ramp?vf=vf= m/s If the ramp is 1.6 m high does it make it to the top?
Under what conditions does a rigid body have angular momentum but not linear momentum?
Luc, who is 1.80 mm tall and weighs 950 NN, is standing at the center of a playground merry-go-round with his arms extended, holding a 4.0 kgkg dumbbell in each hand. The merry-go-round can be modeled as a 4.0-mm-diameter disk with a weight of 1500 NN. Luc's body can be modeled as a uniform 40-cmcm-diameter cylinder with massless arms extending to hands that are 85 cmcm from his center. The merry-go-round is coasting at a steady 35 rpmrpm when Luc brings his hands in to his chest. Afterward, what is the angular velocity, in rpmrpm, of the merry-go-round? The answer is not 31.6 rpm.
Luc, who is 1.80 mm tall and weighs 950 NN, is standing at the center of a playground merry-go-round with his arms extended, holding a 4.0 kgkg dumbbell in each hand. The merry-go-round can be modeled as a 4.0-mm-diameter disk with a weight of 1500 NN. Luc's body can be modeled as a uniform 40-cmcm-diameter cylinder with massless arms extending to hands that are 85 cmcm from his center. The merry-go-round is coasting at a steady 35 rpmrpm when Luc brings his hands in to his chest.
Candace is a 53 kg diver. At the instant of takeoff, her angular momentum about her transverse axis is 20 kg.m7s. Her radius of gyration about the transverse axis is 0.4 m at this instant. During the dive, Candace tucks and reduces her radius of gyration about thetransverse axis to 0.18 m.a) At takeoff, what is Candace's moment of inertia about her transverse axis? kg*m?b) At takeoff, what is Candace's angular velocity in degrees/sec about the transverse axis?c) After Candace tucks, what is her moment of inertia about her transverse axis? kg*m? d) After Candace tucks, what is her angular velocity in degrees/sec about the transverse axis?
A 1 kg rock is suspended from the tip of a horizontal meter stick at the 0 cm mark so that the meter stick barely balances like a seesaw when it’s fulcrum is at the 25 cm mark. From this information the mass of the meter stick is what?
A merry-go-round with a moment of inertia of 880kg⋅m2 experiences a force of 74.5N applied parallel to its edge, which is 3.35m from its axis of rotation. If the force lasts for 6.4s, what is the angular velocity of the merry-go-round, assuming it starts at rest? What is the angular momentum of the merry-go-round at this time?
The cars in a soapbox derby have no engines; they simplycoast downhill. Which of the following design criteria is bestfrom a competitive point of view? The car’s wheels should(a) have large moments of inertia, (b) be massive, (c) behoop-like wheels rather than solid disks, (d) be large wheelsrather than small wheels, or (e) have small moments ofinertia.
A windmill has an initial angular momentum of 8500 kg # m2>s.The wind picks up, and 5.86 s later the windmill’s angularmomentum is 9700 kg # m2>s. What was the torque acting on thewindmill, assuming it was constant during this time?
What is the angular momentum of a .4kg hula-hoop with a diameter of 1.2m while it rotates at 7 r/s?