Answer:
The output power the weightlifter is 2916.67 W.
Explanation:
Given;
weight lifted, W = 700 N
height the weight is lifted, h = 2.5 m
time taken to lift the weight, t = 0.60 s
The output power the weightlifter is calculated as;
Power = Energy applied / time taken
Energy applied = weight lifted x height the weight is lifted
Energy applied = 700 x 2.5
Energy applied = 1750 J
Power = 1750 / 0.6
Power = 2916.67 J/s = 2916.67 W.
Therefore, the output power the weightlifter is 2916.67 W.
the resistance of the cable is 582.9 ohms
we are given the length of the cable which is 3 km, of 1.5 mm in, the diameter and resistivity of copper which is 1.72 m
The formula we are referring to for calculating the resistance of the cable is
R = ρl/A.
As there are 19 strands of copper conductors, so the resistance will be
R = 19( ρl/A)
Here ρ is the resisitivity = 1.72 , l is the length = 3(1+0.05)*10³3= 3150 m
A=pie/4(1.5 x 10⁻³)^2 =1.766 x 10⁻⁶ =1.766 x 10^-6
Substituting the values in the formula we get
R = 19 ( 1.72*3150 )/1.766 x 10⁻⁶
= 582.9 ohm
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Answer:
0.074m/s
Explanation:
We need the formula for conservation of momentum in a collision, this equation is given by,

Where,
= mass of ball
= mass of the person
= Velocity of ball before collision
= Velocity of the person before collision
= velocity of ball afer collision
= velocity of the person after collision
We know that after the collision, as the person as the ball have both the same velocity, then,


Re-arrenge to find
,

Our values are,
= 0.425kg
= 12m/s
= 68.5kg
= 0m/s
Substituting,


<em />
<em>The speed of the person would be 0.074m/s after the collision between him/her and the ball</em>
G = 9.81 m/sec^2) g = 9.81

<span>Solving for velocity : </span>

<span> = 2gh </span>
<span>v = </span>

<span>v = (2 x 9.81 x 10)^1/2 </span>
<span>v = 196.2 m/sec (answer)</span>