Answer:
Both conduction and convection need matter to transfer thermal energy.
Conduction involves collision of particles, while convection involves the movement of a liquid or gas.
Explanation:
There are three ways in which heat is transmitted:
1. By Conduction, when the transmission is by the direct contact (through collisions).
2. By Convection, heat transfer in fluids making a current created by less dense fluids floating and more dense fluids sinking (like water or the air, for example).
3. By Radiation, by the electromagnetic waves (they can travel through any medium and in vacumm)
Therefore, both conduction and convection need matter to transfer thermal energy (unlike radiation).
Answer:

Explanation:
Given that,
The radius of sphere, r = 0.3 m
Distance from the center of the sphere to the point P, x = 0.5 m
Electric field at point P,
(radially outward)
The maximum electric field is at the surface of the sphere. We know that the electric field is inversely proportional to the distance. So,




So, the magnitude of the electric field due to this sphere is 41666.66 N/C. Hence, this is the required solution.
Answer:
Explanation:
Using the efficiency formula;
Efficiency = Work done by the machine (output)/work done on the machine (input) ×100%
Efficiency =w/50 ×100
90 = 100w/50
Cross multiply
90×50 = 100W
4500 = 100W
W = 4500/100
W = 45Joules
Hence the lever does 45Joules of work on its load
2) Mechanical Advantage= Load/Effort
Given
MA = 4
Load = 500N
4 = 500/Effort
Effort = 500/4
Effort =125N
Hence the effort required to lift the load is 125N
Answer: liquids take the shape of the container they are in, but have definite volume. like liquids the shape of a gas changes with the container. unlike liquids the volume of a gas changes depending on the container it is in
Explanation: