work lthe product of force and the amount of displacement along the line of action of that force....
DESCRIPTION
Calculate Work lDuring the ascent phase of a rep of the bench press, the lifter exerts an average vertical force of 1000 N against a barbell while the barbell moves 0.8 m upward lHow much work did the lifter do to the barbell?TRANSCRIPT
WorkWorkThe product of force and the amount
of displacement along the line of action of that force.
Units: Joule (J)
ntdisplacemeForceWork
Work = F x dWork = F x dTo calculate work done on an object, we need:The ForceThe average magnitude of the force The direction of the forceThe DisplacementThe magnitude of the change of positionThe direction of the change of position
Calculate WorkCalculate WorkDuring the ascent phase of a rep of
the bench press, the lifter exerts an average vertical force of 1000 N against a barbell while the barbell moves 0.8 m upward
How much work did the lifter do to the barbell?
Calculate WorkCalculate WorkTable of Variables:Force = +1000 NDisplacement = +0.8 m
Force is positive due to pushing upwardDisplacement is positive due to moving
upward
Calculate WorkCalculate WorkTable of Variables:Force = +1000 NDisplacement = +0.8 mSelect the equation and solve:
JJouleNmWork
mNWorkntdisplacemeForceWork
8008008008.01000
- & + Work- & + WorkPositive work is performed
when the direction of the force and the direction of motion are the sameascent phase of the bench pressThrowing a ballpush off (upward) phase of a jump
Calculate WorkCalculate WorkDuring the descent phase of a rep of
the bench press, the lifter exerts an average vertical force of 1000 N against a barbell while the barbell moves 0.8 m downward
Calculate WorkCalculate WorkTable of VariablesForce = +1000 NDisplacement = -0.8 m
Force is positive due to pushing upwardDisplacement is negative due to
movement downward
Calculate WorkCalculate WorkTable of VariablesForce = +1000 NDisplacement = -0.8 mSelect the equation and solve:
JJouleNmWork
mNWorkntdisplacemeForceWork
8008008008.01000
- & + Work- & + Work Negative work is performed when the direction of the force and the direction of motion are the opposite
descent phase of the bench presscatching landing phase of a jump
Work performed climbing Work performed climbing stairsstairs Work = Fd Force
Subject weightFrom mass, ie 65 kg
Displacement Height of each step
Typical 8 inches (20cm) Work per step
650N x 0.2 m = 130.0 Nm Multiply by the number of steps
Work-energy theorem: Net work = KEΔ
The net external work done on an object equals its change in kinetic energy. This theorem can be proved in relatively few algebra steps from the definitions of work and kinetic energy. KE is the final KE Δminus the initial KE.
PowerPowerThe rate of doing work
Work = Fd
Units: Watt (W)velocityForcePower
tFdPowertimeWorkPower
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