Kicking a soccer ball is work but you need to put power into the kick which is actually moving both your joints and muscles. While working those areas of your body you would most likely be running which I moving your arms and lungs. You are working your hole body and putting stress in every area. This is why kicking a soccer ball is work.
Answer:
Δt=0.85 seconds
Explanation:
In this chase the speed does not change as the mass change.So we can use the follow equation to find the required time
Δt=Δv/gμ
To stop the final speed will be zero therefore the change in speed will be
Δv= vf-vi
Δv=0-5 m/s
Δv= -5 m/s
Now we plug our values for Δv,g and μ to find time
Δt=Δv/gμ
Δt=(-5m/s) ÷(9.8m/s² × 0.6)
Δt=0.85 seconds
Answer:
T = 480.2N
Explanation:
In order to find the required force, you take into account that the sum of forces must be equal to zero if the object has a constant speed.
The forces on the boxes are:
(1)
T: tension of the rope
M: mass of the boxes 0= 49kg
g: gravitational acceleration = 9.8m/s^2
The pulley is frictionless, then, you can assume that the tension of the rope T, is equal to the force that the woman makes.
By using the equation (1) you obtain:
The woman needs to pull the rope at 480.2N
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Answer:
v = 2.31 m/s
Explanation:
Kinetic energy will be converted partially into potential energy and rest will remain in the form of kinetic energy .
Initial kinetic energy = 1/2 mu²
u is initial velocity at the bottom .
Potential energy at the top
= mgh
Kinetic energy at the top
= 1/2 m v²
According to conservation of energy
1/2 mu² = mgh + 1/2 m v²
1/2 u² = gh + 1/2 v²
.5 x 4.5² = 9.8 x .76 + .5 v²
10.125 = 7.448 + .5 x v²
v = 2.31 m/s