Question

mission w14: mechanical energy
suppose an object moves downward with a
decreasing speed. in this situation, the objects kinetic
energy would __, its potential energy would __,
and its total mechanical ener would ____. enter the
three letters in their respective order.
a. increase
b. decrease
c. remain the same
d. ... nonsense! it is impossible to tell without
additional info.

Explanation:

Step1: Analyze kinetic energy

Kinetic energy formula is \(K = \frac{1}{2}mv^{2}\). Since the speed \(v\) is decreasing and mass \(m\) is constant, kinetic energy \(K\) decreases.

Step2: Analyze potential energy

The object is moving downward. For gravitational potential energy \(U = mgh\) (assuming gravitational potential energy), as height \(h\) decreases, potential energy \(U\) decreases.

Step3: Analyze total mechanical energy

If there is non - conservative force (like air resistance, because the object is decelerating while moving down, which means a force opposite to the motion is acting). According to \(E_{total}=K + U+E_{other}\) (where \(E_{other}\) is the energy due to non - conservative forces). Since non - conservative force does negative work (as it is opposite to the direction of motion), total mechanical energy \(E_{total}=K + U\) decreases.

Answer:

b, b, b