B
A quantity that has magnitude and direction.
Hi!
The energy of the block is 4 m/s
To calculate this, you need to use the equation for
kinetic energy. The block is sliding (i.e. it's moving). If the object is sliding across a level surface, the only energy it has is kinetic energy, because
there is no change in potential energy (which changes with height). So, the mechanical energy will be pure kinetic energy. The equation is the following, derived from the expression for kinetic energy:

Have a nice day!
Taking notes,because you can read back on what you learned
Answer:
40 j, 80j.
Explanation:
P.E= mgh. G=10 m/s².
For 4m, P.E=1*10*4=40 joules.
For 8m, P.E=1*10*8=80 joules.