Answer:
A) The sum of the kinetic energy and the gravitational potential energy changes by an amount equal to the energy dissipated by friction,
Explanation:
- The kinetic energy is the energy that the object has and is defied by the work that is needed to accelerate the body.
- The gravitational potential is a mechanism by which an equal amount of energy is being transferred per unit mass that is needed for the object to move from the specific location.
- Hence when the sled moves down the hill with the force of gravity it has negligible resistance as an equal amount of energy is dissipated.
348.34 m/s. When Superman reaches the train, his final velocity will be 348.34 m/s.
To solve this problem, we are going to use the kinematics equations for constant aceleration. The key for this problem are the equations
and
where
is distance,
is the initial velocity,
is the final velocity,
is time, and
is aceleration.
Superman's initial velocity is
, and he will have to cover a distance d = 850m in a time t = 4.22s. Since we know
,
and
, we have to find the aceleration
in order to find
.
From the equation
we have to clear
, getting the equation as follows:
.
Substituting the values:

To find
we use the equation
.
Substituting the values:

Answer: Look where the points are.
Explanation: