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Answer:
619.8 N
Explanation:
The tension in the string provides the centripetal force that keeps the rock in circular motion, so we can write:
where
T is the tension
m is the mass of the rock
v is the speed
r is the radius of the circular path
At the beginning,
T = 50.4 N
v = 21.1 m/s
r = 2.51 m
So we can use the equation to find the mass of the rock:
Later, the radius of the string is decreased to
r' = 1.22 m
While the speed is increased to
v' = 51.6 m/s
Substituting these new data into the equation, we find the tension at which the string breaks:
Answer:
Both of you did the same work but you expended more power.
Explanation:
<em>Work done</em> by an object is calculated by force applied multiplied by the distance.
W=F*d
From the figure given below let us calculate force applied bith you and yopur friend.
Let us take the stairs in positive x direction,
Work done by you W₁ ,
The force applied Fₓ = F - mgsinθ =maₓ
here aₓ = 0, because both of you move with constant speed
F - mgsinθ = 0
F= mgsinθ
The work done by you on the suitcase is
W = F L cos0° , where L is he length of the staircase.
W = FL = mgsinθL , by substituting value of F
Work done by you is W₁ = mgLsinθ
Similarly work done by your friend is W₂ = mgLsinθ.
Because both of you carry suitcase of same weight and in staircase is in same angle the force applied is same .
Therefore <em>work done by both of you is same</em> . Both of you did equal work.
The power , is defined as amount of energy converted or transfered per second or rate at which work is done .
P = =
Power spend by you P₁ = mgLsinθ/t
P₁ = 15*9.8*Lsinθ/30
P₁ = 4.9L sinθ eqn 1
Power spend by your friend is P₂ = mgLsinθ/t
P₂ =15*9.8*Lsinθ/60
P₂ = 2.45Lsinθ eqn 2
Dividing eqn 1 and eqn 2
P₁ = 2P₂
You have spend more power than your friend .
Hence Both of you did equal work but you spend more power.
