The speed of a car travelling over a hill that has a radius of curvature should not exceed a certain speed other it will topple. This speed is related to the radius of curvature and the gravitational acceleration as shown below:
V^2 = Rg, where V = maximum speed, R = Radius of curvature, g = gravitational acceleration.
Substituting;
V = Sqrt (Rg) = Sqrt (120*9.81) = 34.31 m/s
The mass of the object does not change by moving it to another place. ... At the center of the earth the net gravitational force is zero, so the weight will be zero, but its masses will remain same. Hence the mass at the centre of earth will be equl to 50 kg.
Answer:
1.55 m
Explanation:
The potential produced by a point charge, is inversely proportional to the distance from the charge to the point where the potential is being calculated, as follows:

As it only depends from the distance r, we can conclude that if the potential is the same for any point to a distance r from the point charge, the equipotencial surface must be a sphere of radius r.
Replacing q = +1.7*10⁻⁸ C, and k = 9*10⁹ N*m²/C², and V, by 120 V and 54 V, we can find the distance from the charge, to the points where we are calculating the potential V, as follows:


The distance between both points, is just the difference between the radius of both spheres, as follows:
r₂ - r₁ = 1.55 m
Work is done when a force is in the same direction as the object moves.
Explanation:
The work done by a force in moving an object is given by the equation

where
F is the magnitude of the force
d is the displacement of the object
is the angle between the directions of F and d
From the equation, we notice the following:
- Work is done by a force when the force is in the same direction as the object moves. In fact, in this case,
, and so
, which means that the work done simply becomes 
- When the force is perpendicular to the motion of the object,
and
, which means that no work done - Technically, work is also done when the force is not parallel to the motion of the object: in this case, the factor
means that only the component of the force parallel to the direction of motion contributes to do work on the object.
Therefore, the correct answer is
Work is done when a force is in the same direction as the object moves.
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