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:
2 seconds
Explanation:
if a ball travels 1/2 meter per second, and there's 2 halfs in a whole, 1/2 meter per second x 2 halfs in a whole meter is 2 seconds to travel a meter
<em>Convert 1nanosecond in to its SI init</em>
<em>In SI units, nano is 1000th part of micro which in turn is 1000th part of mini which in turn is 1000th part of main unit. Now, when you affix nano to any unit, here in case, second, it means that you are referring to 1000th part of 1000th part of 1000th part of second or in short, 1000000000th(10^9) part of a second.</em>
<em>In SI units, nano is 1000th part of micro which in turn is 1000th part of mini which in turn is 1000th part of main unit. Now, when you affix nano to any unit, here in case, second, it means that you are referring to 1000th part of 1000th part of 1000th part of second or in short, 1000000000th(10^9) part of a second.So to convert nanosecond into second, just multiply the nanosecond with 0.000000001 or (10^-9)</em>
Answer:
The maximum force on the supporting cable is 80688 N.
The minimum force on the supporting cable is -164 N.
Explanation:
For maximum force movement of elevator is in upward direction. Thus, equation of motion is given by,
ma = T - mg
where m is the mass of elevator
a is acceleration of elevator
g is acceleration due to gravity
T is the maximum tension in the supporting cable
T = ma + mg
T = m (a + g)
T = 4100 ( 0.04g + 9.8)
T = 80688 N
This is the maximum force on the supporting cable.
For minimum force movement of elevator is in downward direction. Thus, equation of motion is given by,
ma = T - mg
where m is the mass of elevator
a= -0.04g is acceleration of elevator because elevator is moving downward
g is acceleration due to gravity
T is the minimum tension in the supporting cable
T = ma + mg
T = m (a + g)
T = 4100 ( 9.8 - 0.04g)
T = -164 N
This is the minimum force on the supporting cable.
