Answer:
The total work on the ball is 36.25 Joules
Explanation:
There is an important principle on classical mechanics that is the work-energy principle it states that the total work on an object is equal the change on its kinetic energy, mathematically expressed as:
(1)
With W net the total work, Kf the final kinetic energy and Ki the initial kinetic energy. We're going to use this principle to calculate the total work on the baseball by the force exerted by the bat.
Kinetic energy is the energy related with the movement of an object and every classical object with velocity has some kinetic energy, it is defined as:

With m the mass of the object and v its velocity, knowing this we can use on:
In our case vf is the velocity just after the hit and vi the velocity just before the hit. For an average baseball its mass is 145g that is 0.145 kg, then

Answer:
90 km/h
Explanation:
we just divide the distance by the time to get the speed.
The 2 positively charged particles would repel each other.
4.0 cm
Hope this helps (:
Answer:
B) The tree was stationary and began to move.
Explanation:
This situation can be explained by using Newton's first law of motion, which states that
"An object at rest (or in motion at constant velocity) stays at rest (or in motion at constant velocity) unless a net non-zero force is exerted on it"
This means that an object at rest can start moving if and only if there is a net non-zero force acting on it.
In the example in the problem, the tree is initially stationary. Later, it started to move. According to Newton's first law, therefore, there must be a net force that caused this change of state of motion of the tree. Therefore, the correct answer is
B) The tree was stationary and began to move.