By Newton's second law, the net vertical force acting on the object is 0, so that
<em>n</em> - <em>w</em> = 0
where <em>n</em> = magnitude of the normal force of the surface pushing up on the object, and <em>w</em> = weight of the object. Hence <em>n</em> = <em>w</em> = <em>mg</em> = 196 N, where <em>m</em> = 20 kg and <em>g</em> = 9.80 m/s².
The force of static friction exerts up to 80 N on the object, since that's the minimum required force needed to get it moving, which means the coefficient of <u>static</u> friction <em>µ</em> is such that
80 N = <em>µ</em> (196 N) → <em>µ</em> = (80 N)/(196 N) ≈ 0.408
Moving at constant speed, there is a kinetic friction force of 40 N opposing the object's motion, so that the coefficient of <u>kinetic</u> friction <em>ν</em> is
40 N = <em>ν</em> (196 N) → <em>ν</em> = (40 N)/(196 N) ≈ 0.204
And so the closest answer is C.
(Note: <em>µ</em> and <em>ν</em> are the Greek letters mu and nu)
Answer:
166 W
Explanation:
Power is the rate at which work is done.
The work done by Jill is the product of the weight of the pail and the height it moves.
The weight is the product of the mass and acceleration of gravity, <em>g</em>. Taking <em>g</em> as 9.81 m/s², the weight is
<em>W</em> = (6.90 kg)(9.81 m/s²) = 67.689 N
Work done = (67.689 N)(27.0 m) = 1827.603 J
Power = (1827.603 J) ÷ (11.0 s) = 166 W
Answer:
Explanation:
Muscle cells are excitable; they respond to a stimulus.meaning they can shorten and generate a pulling force. When attached between two movable objects, such as two bones, contraction of the muscles cause the bones to move.It contains protein fibers which contract to make the cell shorter.
Answer:
The force F is created by the reaction of the Earth to the thrust of the rods, whereby the thrust is created by a force of action and reaction.
Explanation:
To answer this question, let's write Newton's second law of the two axes
Y Axis
Fy + N - W = 0
Fy + N = W
X axis
Fx - fr = 0
Fx = fr
The force F is created by the reaction of the Earth to the thrust of the rods, whereby the thrust is created by a force of action and reaction.
The direction of this force is along the length of the rods that are in an Angle, where the x and y components of the force come from
In general this force is small because the rubbing of the skis is small
