Answer:
An element is a pure substance and is made of only one type of atom.
Explanation:
It cannot be broken down into a simpler substance.
Answer:
For cast iron we have

For copper

For Lead

For Zinc

Explanation:
As we know that final speed of the block is calculated by work energy theorem

now we have

now we have


For cast iron we have


For copper


For Lead


For Zinc


Answer:
The wave speed is calculated below:
Explanation:
Given,
number of waves passed per minute = 8
time period = 1 minute = 60 s
distance between successive wave crests = 20 m
waves passing interval per second =

Now,
wave speed = 20 m ×

=
m/s
= 2.67 m/s
Hence the wave speed is 2.67 m/s.
The answer is letter c.
The explanation behind this is when human consumes a plant
or when a human being eats an animal that ate a plant. The chemical energy kept
in the plant (or animal) cells is progressed into the cells of the human's
body. All of the body progressions, like ingestion, breathing, pumping blood, are
driven by cells changing the kept chemical energy into heat and work, in a procedure
called respiration. In the muscle cells of the human (or any animal), the
chemical energy is converted into mechanical work and heat. The muscle pacts,
the legs thrust, and the body jumps into the air.
<span>The Sun and all the planets revolve around Earth.</span>