A gymnast of mass 70.0 kg hangs from a vertical rope attached to the ceiling. You can ignore the weight of the rope and assume t
1 answer:
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Answer:
20m
6.9s
Explanation:
The vertical velocity of the ball is 20m/s. We can calculate the kinetic energy which gets transferred to potential energy once it gets to the top.
we can subtitute v = 20m/s and g = 10m/s2
So the ball could go 20m high from the child hand, or 120m fro the bottom of the cliff.
The time it takes for the ball to travels to the top is the time it takes for it to decelerate from 20m/s to 0m/s with gravitational deceleration g = 10m/s2
t = v / g = 20 / 10 = 2s
Then the ball will start accelerating down ward with a constant acceleration of g = 10m/s. In order to cover distance d of 120m from the top to the bottom of the cliff
So the total time it takes is 4.9 + 2 = 6.9s
Lower mass: 1.20 kg, upper mass: 1.28 kg
Explanation:
In order to solve the problem, we consider the forces acting on the upper mass only first.
The upper mass is acted upon three forces:
- The applied force
, upward
- The weight of the mass itself,
, where
is the upper mass and
is the acceleration of gravity, downward
- The tension in the string,
, downward
Therefore, the equation of the forces for the upper mass is:
where
is the acceleration (upward)
Solving for ,
Now we can find the lower mass by considering the forces acting on it:
- The tension in the string, T = 16 N, upward
- The weight of the mass itself,
, where
is the lower mass, downward
So the equation of the forces is
And solving for the mass,
Learn more about acceleration and forces:
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