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1 answer:
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Answer:
Work done, W = 2675.4 J
Given:
mass, m = 70.0 kg
height, H = 3.90 m
Solution:
According to the question, as the person jumps the stairs up, there is an increase in the potential energy of the person which is provided by the work done in climbing the stairs and is given by:
Work done, W = mgH
where
g = acceleration due to gravity =
The minimum speed of the water must be 3.4 m/s
Explanation:
There are two forces acting on the water in the pail when it is at the top of its circular motion:
- The force of gravity, mg, acting downward (where m is the mass of the water and g the acceleration of gravity)
- The normal reaction, N also acting downward
Since the water is in circular motion, the net force must be equal to the centripetal force, so:
Where:
v is the speed of the pail
r = 1.2 m is the radius of the circle
The water starts to spill out when the normal reaction of the pail becomes zero:
N = 0
When this occurs, the equation becomes:
And substitutin the values of g and r, we find the minimum speed that the water must have in order not to spill out:
Learn more about circular motion:
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Answer:
v₂ = 0.56 m / s
Explanation:
This exercise can be done using Bernoulli's equation
P₁ + ½ ρ v₁² + ρ g y₁ = P₂ + ½ ρ v₂² + ρ g y₂
Where points 1 and 2 are on the surface of the glass and the top of the straw
The pressure at the two points is the same because they are open to the atmosphere, if we assume that the surface of the vessel is much sea that the area of the straw the velocity of the surface of the vessel is almost zero v₁ = 0
The difference in height between the level of the glass and the straw is constant and equal to 1.6 cm = 1.6 10⁻² m
We substitute in the equation
+ ρ g y₁ =
+ ½ ρ v₂² + ρ g y₂
½ v₂² = g (y₂-y₁)
v₂ = √ 2 g (y₂-y₁)
Let's calculate
v₂ = √ (2 9.8 1.6 10⁻²)
v₂ = 0.56 m / s