How much force is needed to accelerate a 68 kilogram-skier at a rate of 1.2 m/sec^2?
2 answers:
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One of the essential concepts to solve this problem is the utilization of the equations of centripetal and gravitational force.
From them it will be possible to find the speed of the body with which the estimated time can be calculated through the kinematic equations of motion. At the same time for the calculation of this speed it is necessary to clarify that this will remain twice the ship, because as we know by relativity, when moving in the same magnitude but in the opposite direction, with respect to the ship the debris will be double speed.
By equilibrium the centrifugal force and the gravitational force are equal therefore
Where
m = mass spacecraft
v = velocity
G = Gravitational Universal Constant
M = Mass of earth
Radius of earth and orbit
Re-arrange to find the velocity
Replacing with our values we have
From the cinematic equations of motion we have to
Remember that the speed is double for the counter-direction of the trajectories.
Replacing
Therefore the time required is 3.778s
Answer:
The pressure on the ground is about 9779.5 Pascal.
The pressure can be reduced by distributing the weight over a larger area using, for example, a thin plate with an area larger than the circular area of the barrel's bottom side. See more details further below.
Explanation:
Start with the formula for pressure
(pressure P) = (Force F) / (Area A)
In order to determine the pressure the barrel exerts on the floor area, we need the calculate the its weight first
where m is the mass of the barrel and g the gravitational acceleration. We can estimate this mass using the volume of a cylinder with radius 30 cm and height 1m, the density of the water, and the assumption that the container mass is negligible:
The density of water is 997 kg/m^3, so the mass of the barrel is:
and so the weight is
and so the pressure is
This answers the first part of the question.
The second part of the question asks for ways to reduce the above pressure without changing the amount of water. Since the pressure is directly proportional to the weight (determined by the water) and indirectly proportional to the area, changing the area offers itself here. Specifically, we could insert a thin plate (of negligible additional weight) to spread the weight of the barrel over a larger area. Alternatively, the barrel could be reshaped (if this is allowed) into one with a larger diameter (and smaller height), which would achieve a reduction of the pressure.