A rope is being used to pull a mass of 10kg vertically upward. Determine the tension in the rope if, starting from rest, the mass acquires a velocity of 4ms\(^{-1}\) in 8s [g = 10ms\(^{-2}\)]
5N
50N
95N
105N
Explanation
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Discussions (30)
If the body is moving upward the tension would
be T = W + ma
If the body is moving downward the tension
would be T = W - ma
If the tension is equal to weight of body T = W.
.. W=mg
Where m = mass of the body,
g = acceleration due to gravity,
a = acceleration of the moving body.
For the question, T=mg+ma, m=10kg, g=10, a=△v/t....4/8=0.5...therefore T=mg---»10x10=100 + ma--»(10x0.5)=5...100+5=105
The selected answer is wrong:
Why wasn't acceleration due to gravity(g) used. I don't agree with the answer. The formulae user was also wrong. Normally T-mg=ma; T=mg+ma=10×4/8+10×10=40/8+100=5+100=105N
REF: Check new school physics
Note: It decreases upward while increases downwards.
-> mg - ma
(10*10) - (10*4/8)
= 100 - 5
= 95N
try this one too
mass=10kg
velocity =4m\s
Time=8s
solution
acceleration = change of velocity /time taken
a=4/8=0.5
when lift is accelerating upward
weight of body =mg+ma
=m(g+a)
10(10×0.5)=100.5,,,
the answer selected is only applicable if the string was static but since it was pulled upwards formula is gonna be T= the weight (mg) + Force (ma)
well my explanation is like this
mass=10kg
velocity =4m\s
Time=8s
solution
acceleration = change of velocity /time taken
a=4/8=0.5
using F = tension in the rope
from F= ma
Tension, F=(10×0.5)=5
weight of body due to gravity
=mg
5×10=50
