g = 9.80 m/s2 G=6.67×1011 Nm? / kg? c-2.99792458 x108 m/s Reart-6371 km [Notice
ID: 1789322 • Letter: G
Question
g = 9.80 m/s2 G=6.67×1011 Nm? / kg? c-2.99792458 x108 m/s Reart-6371 km [Notice that this is not in base SI units! Marth-5.98 × 1024 kg The drawing shows a person (weight 584N) doing push ups. Assuming lefU/right body symmetry, and also that the person holds this position; find L:The torque (both magnitude in Nm and direction) caused by gravity, relative to the axis into the paper through the persons toes. Include units. 02:The normal force (magnitude in N and direction) exerted by the floor on each hand. (Hint: How many hands does he have?) Include units. Gravity acts through CG, not through the hands! 0.840 m 0.410 mExplanation / Answer
If the person holds the position, then there is no acceleration nor rotation, so we have vertical and rotational equilibrium.
Vertical equilibrium tells us all vertical forces are balanced, which means
2F+2H=584 where F is he force of the floor on each foot and H is the force of the floor on each hand; dividing by 2:
F+H=292
the sum of torques is also zero; if we sum torques around the feet, we have
sum of torques = 584 L1 + 2H (L1+L2) =0
Torque = 584*0.84 = 490.56 N.m
the force F exerts no torque around the feet since F has no lever arm around the feet
substituting numbers, we have
584x0.840+2H(0.840+0.410)=0
H=196.224 N
since H+F=292 N, F=95.776 N
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