A 13-kg sled is moving at a speed of 3.0 m/s. At which of the following speed will the sled have twice as much kinetic energy?
4.2 m/s
Let us list out what we know from the question.
Initial Velocity
since the piton is 'dropped'.
Vertical Displacement of the piton D = 215 m
Acceleration due to gravity 
Final Velocity 
Using the equation,
and plugging in the known values, we get

Simplifying by taking square-root on both sides gives us 
Thus, the speed of the piton just before striking the ground is 65 m/s.
Ice floating on water and Ice floats on water because it is less dense than water. Things that are less dense float on top of things that are more dense because molecules in ice are further apart than molecules in water.
Answer:
False
Explanation:
The roller displacement at an external, friction less rotation pin is found to be zero as it has a support which is no-yielding but still provides rotation to the object where as at an external pin a shear force is present and the moment is absent which means that at an external pin its not the rotation that is absent but its the moment which comes out to be zero.
Nuclear reaction you are literally splitting an atom and in a chemical reaction you are not