Hello,
The answer is A) a mixture. An element as defined as a pure substance, that cannot be broken down and most are typically naturally occurring. A compound occurs in chemical bonding. A substance is either a pure element or compound.
Answer:
2.66m/s
Explanation:
information we have
power: 65W
work per step per kilogram: 0.60J
mass: 61kg
length of a running step: 1.5m
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the formula for power is:

where W is the work and t is time.
time is also defined as: 
so substituting this into the formula for power we get:

where v is the velocity we are looking for, d is the distance per step:
, W is the work per step and P is power
.
we know that the work per step per kilogram is:
0.60J
so to find the work per step of his whole body we need to multiply the 0.60J by the 61 kilograms of his mas:
this is the work per step of the person.
So now we can calculate the velocity using the formula for power

clearing for v:

and substituting known values:

Answer:
light is an example of a wave that is not mechanical .
it is different as it does not need material medium for its propagation
Answer:
Protons and neutrons are all attracted to each other as a result - the strong nuclear force. This is an attractive force that only has an effect over a very short range in the nucleus.