Their relative speed is the sum of 60 and 40 or 100km/hr. They will travel the 150km in 1.5 hrs. When two object approach each other, the closing speed is just the sum of the speeds, therefore, the closing speed is your case is 100kph. So they will meet in 1.5 hours.
When using a simple machine, the benefit of using less force to lift an object is offset by the need to push for a larger distance so that energy can be conserved.
<u>Explanation:
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A simple machine utilized for completing the works easily. So in order for easy and quick completion of works, these machines may increase the amount of force acting on the object by increasing the velocity or speed of the machine. As velocity term is present so the machines may also change the directions of force acting on the object of concern to do the work soon just like pulley.
Also other way of completing the work with less input force requirement is by increasing the distance or area of action for the force acting on it. As work done is a measure of acting force on a region multiplied with the displacement occurred with that force.
It can be known that force seems to be inversely proportional to distance or area of action. So if we need to use less force to lift an object, it is offset by the need to push for a larger distance in order to conserve the energy.
To solve this problem it is necessary to apply the equation related to the Gravitational Force, the equation describes that
Where,
G = Gravitational Universal Constant
M = Mass of Earth (or Bigger star)
m = Mass of Object (or smallest star)
r = Radius
From the statement we know that once the impact is made, the golf ball is subjected to the forces that are exerted in nature. Since the air resistance, which would represent the drag force, is ignored. Only the forces related to gravity remain.
The gravitational force carries 'pushes' or 'attracts' the body towards the earth, while the speed decreases as it reaches its maximum height.
When the ball has reached its maximum height only the force of gravity begins to act on it, generating the attraction to the earth in parabolic motion.
Therefore the correct answer is B.
