Answer:
D. crystalline solid that conducts current under certain conditions
Explanation:
Semiconductors are crystalline solids that has the ability to conduct electrical currents but on certain conditions e.g heat. The conduction of semiconductors is less than that of conductors (metals) but more than insulators (nonmetals), hence, they are said to be intermediates of conductors and insulators in terms of electrical conductivity.
Examples of semiconductors are silicon, boron, carbon, germanium, arsenic etc.
3. Millions of years ago, the Earth was not divided into 7 continents. It was only a very large land mass, the scientists named that one land mass “Pangaea”
4. If the tectonic plates are disturbed, they can cause mass earthquakes and tsunamis.
5. The ring of fire is a massive collection of volcanoes under the pacific ocean. They all form the shape of a ring, hence the name.
SORRY, I COULDNT ANSWER THE FIRST TWO QUESTIONS.
When we set something down on the ground, the kind of work that our arms doing is : negative apex
It's happen whenever we do works that are align with the force of Gravity (to the bottom)
hope this helps
Answer:
29223.6J
Explanation:
Given parameters:
Mass of Piano = 852kg
Height of lifting = 3.5m
Unknown:
Gravitational potential energy = ?
Solution:
The gravitational potential energy of a body can be expressed as the energy due to the position of a body;
G.P.E = mgh
m is the mass
g is the acceleration due to gravity
h is the height
Now insert the given parameters and solve;
G.P.E = 852 x 9.8 x 3.5 = 29223.6J
Answer:
We would not be able to make our way around the earth's surface, to read, to sculpt or to create technology because we cannot see!
Explanation:
The minimum angular separation that can be distinguished by an eye gives the angular resolution of the eye.
Given that the Angular resolution with infrared radiation is = 
equal to 
This resolution is very much greater than that of the eye 
The angular resolution that our eyes can see is about 
at arms length
Angular resolution of infrared = 
at arms length
We therefore cannot read, sculpt or create technology because we cannot see.
