A Levels Physics

A mass at point X inside a uniform gravitational field experiences a gravitational force of 0.200 N.
It has 1.00 J of gravitational potential energy.
30 cm
uniform
50 cm
gravitational
field
The mass is then moved to point Y.
What is its new gravitational potential energy?
A 0.90 J
B 0.94 J
C 1.06J
D
1.10 J


Choice C is correct because:

The gravitational potential energy (U) of an object in a uniform gravitational field is given by the equation:  where m is the mass of the object, g is the gravitational field strength, and h is the height above the reference point.

The change in gravitational potential energy can be found by .

The weight is 0.200 N and the change in height parallel to the field s 30 cm or 0.3 m.

Therefore,.

So the new gravitational potential energy is . 

Choice A is incorrect because:

Choice A suggests a new potential energy of 0.90 J, which is lower than the initial potential energy. This is inconsistent with the fact that the object is moved to a higher position in the gravitational field.

Choice B is incorrect because:

Choice B suggests a new potential energy of 0.94 J, which is also lower than the initial potential energy. This is inconsistent with the fact that the object is moved to a higher position in the gravitational field.

Choice D is incorrect because:

Choice D suggests a new potential energy of 1.10 J, which is higher than the calculated new potential energy of 1.06 J. This suggests an overestimation of the increase in height or an error in the calculation.

Work, Energy and Power | 2014 - M/J - 9702/12 | Q14