Answer:
1. Two materials that can be scratched by an iron nail are <u>zinc</u> and <u>aluminum</u>
2. A substance that can be scratched by an iron nail but not a penny is;
Nickel
Explanation:
The hardness of a material can be defined as its ability to resist being plastically deformed at a location due to mechanical scratching, abrasion or indentation
The Mohs hardness scale provides a ranking of materials in the order of hardness with a material having a higher Mohs hardness number being able to scratch other materials which have a lower Mohs hardness number
1. From the Mohs scale of hardness, iron which has an harness number of 4.5 can scratch zinc which has an harness number of 2.5, and iron can also scratch aluminum which has an hardness number of 2.5 to 3
2. A penny is made from copper plated material and will have an outer layer hardness of copper which has an hardness number of 3 on the Mohs scale
Therefore, a penny cannot scratch a material mode of nickel which has an hardness number of 4, while iron which has an hardness of 4.5 will scratch a nickel material
4. No motion
5. Threre will be movement in one direction or another
Efficiency of a simple machine is the ratio of mechanical advantage and speed ratio.
If mechanical advantage = speed ratio then efficiency = 1
Which is impossible for a practical machine due to presence of frictional force which wastes some energy and thus lowers the output
Answer:
Explanation:
Option a is correct
If puck and pick constitute a system then the momentum of the system is conserved but not this may not be valid for the puck .
Option e is correct
If puck and pick is the system then momentum is conserved but because of the presence of friction, mechanical energy is not conserved.
Friction will cause the energy to dissipate in heat.