Question

An object A with a kinetic energy of 800 joules moving horizontally is subjected to a force of 100 Newtons, which is the opposite of motion as it moves from point X to point Y. XY distance is 2 m. What is the energy of A at point Y?

Answer 1

Answer:

d = 8 [m]

Explanation:

To solve this problem we must use the principle of conservation of energy, where the mechanical energy in a state plus the work done on the body, must be equal to the mechanical energy in the state Y. This can be easily represented in the following equation.

$E_{x}+W_{x-y}=E_{y}$

where:

Ex = Mechanical energy in X [J]

Wx-y = Work among states x and y [J]

Ey = Mechanical energy in Y [J].

The key to being able to understand this problem is that in state X, we only have kinetic energy, while the energy in state Y is equal to zero (there is no movement). The work is equal to the product of force by distance, as work acts in the opposite direction to movement, this has a negative sign.

$800 - F*d = 0\\100*d = 800\\d = 800/100\\d = 8 [m]$