Answer:
Option C or the third option.
Explanation: Water is a renewable resource there is so much of it and it just keeps circulating through the system it doesn't run out.
The radiation is ultra voilet or Gamma radiation , because their wave length is very short i e 1..0 to 2.5 (angstrom)Ao.
Answer:
Friction between the box and the floor is 25N to the left
Explanation:
There are two forces acting on the box along the horizontal direction:
- The force of push applied by the worker, in the forward direction, F
- The force of friction, 
, acting in the opposite direction (backward)
So the net force acting on the box is
According to Newton's second law of motion, the net force on an object is equal to the product between its mass (m) and its acceleration (a), so we can write:
And so
However, in this case the box is moving at constant speed; this means that its acceleration is zero:
Therefore we have:
Which means
And since we are told that
This means that the force of friction is also 25 N:
-- There's a force of 240N pushing her backwards.
-- She's maintaining a steady speed (of 2.5 m/s) .
-- In order to maintain a steady speed (no acceleration),
the forces on her must be balanced. So she's maintaining
a steady force of 240N forward.
-- Every time she moves 1 m forward, she does work of
(force) x (distance) = 240 joules.
-- She moves 2.5 meters forward every second.
So she's doing (240 x 2.5) = 600 joules of work every second.
-- 600 joules per second = 600 watts .
This question deals with the law of conservation of momentum, which basically says that the total momentum in a system must stay the same, provided there are no outside forces. Since you were given the mass and velocity of the two objects you can find the momentum (p=mv) of each and then add them together to find the total momentum of the system before they collide. This total momentum must be the same after they collide. Since you have the mass and velocity of one of the objects after the collision you can find the its momentum after. Subtract this from the the system total and you will have the momentum of the other object after the collision. Now that you know the momentum of the other object you can find its velocity using p=mv and its mass from before.
Be careful with the velocities. They are vectors, so direction matters. Typically moving to the right is positive (+) and moving to the left is negative (-). It is not clear from your question which direction the objects are moving before and after the collision.
