15 joules of work are done by forces other than gravity in taking an object from a position 3 m above the ground to a position 8 m above the ground. What is the change in the gravitational potential energy of the object?
o A. It decreases by 5 joules.
o B. It increases by 5 joules.
o C. It increases by 11 joules.
o D. It increases by 15 joules.
Correct Answer: D — It increases by 15 joules.
Explanation: The amount of work done by non-gravitational forces in moving an object from one position to another is equal to the change in the gravitational potential energy of the object. If 15 joules of work are done on the object by non-gravitational forces, then the gravitational potential energy of the object is increased by 15 joules.
Well, the change in gravitational potential energy can be calculated using the formula ΔPE = mgh, where m is the mass of the object, g is the gravitational acceleration, and h is the change in height.
Given that the work done by forces other than gravity is 15 joules, we know that the total work done on the object is 15 joules. And since work is also equal to ΔPE, we can conclude that the change in gravitational potential energy is 15 joules.
But hold on a second! The question asks for the change in gravitational potential energy specifically when the object is moved from a position 3 m above the ground to a position 8 m above the ground.
So, the object starts at a height of 3 m and ends up at a height of 8 m. The change in height, h, is 8 m - 3 m = 5 m.
Now let's plug in the values into the formula: ΔPE = mgh. Since we don't have any information about the mass of the object, we can't calculate the exact change in gravitational potential energy. So, unfortunately, the answer cannot be determined from the given information.
I apologize for not being able to give you a specific answer, but I hope I at least provided some clarity on the concept!
To find the change in gravitational potential energy, we need to calculate the difference in potential energy at the initial and final positions. The formula for gravitational potential energy is given by:
Potential Energy (PE) = mgh
Where:
m = mass of the object
g = acceleration due to gravity (approximately 9.8 m/s^2)
h = height
In this case, the work done by forces other than gravity is 15 joules. This work is equivalent to the change in potential energy, so:
Work = Change in Potential Energy
15 joules = Change in Potential Energy
Since the object is moved vertically upwards, the change in height (h) is given by the difference in height between the final and initial positions, which is 8 m - 3 m = 5 m.
So, the change in potential energy is 15 joules.
Therefore, the correct answer is:
o A. It decreases by 5 joules.
To find the change in gravitational potential energy of the object, we need to know the object's mass and the acceleration due to gravity. However, these values are not given in the question.
But we can use the formula for gravitational potential energy to solve this problem. The formula for gravitational potential energy is:
Gravitational Potential Energy = mass * gravity * height
Since we don't know the mass or gravity, we can cancel them out by comparing the initial and final heights of the object.
Given that the object is moved from a position 3 m above the ground to a position 8 m above the ground, we can see that the object is raised vertically. This means that the work done on the object is entirely due to the gravitational force.
Since the work done by forces other than gravity is given as 15 joules, the change in gravitational potential energy of the object is equal to the work done:
Change in Gravitational Potential Energy = Work done = 15 joules
So, the correct answer is:
o A. It decreases by 5 joules.