Answer:
Explanation:
At thermal equilibrium we have heat given by aluminium must be equal to the heat absorbed by the water
so we will have
so we will have
so we have
so we have
Answer:
A. Remove everything in the refrigerator to lighten the load.
B. Put a lubricant between the surface of the object and the floor
C. Use round objects, like pencils , to decrease the friction and push the refrigerator over the pencils more easily
Explanation:
Force of friction is a resistance force which acts between two surfaces which are in relative motion. Friction is both boon and bane. Due to friction, we are able to sit, walk etc but also, due to friction there is dissipation of energy. Friction can be reduced by applying lubricants, reducing contact area, reducing the load.
F = μN where N is the normal force which depends on the mass.
Thus, by reducing the load, force of friction can be reduced. Round objects like wheels can also be used. By this the contact area reduces.
Answer:
Only option A is correct
Explanation:
From the concept of Doppler effect, only speed matters. Thus, the faster a vehicle is moving, the closer together the sound waves get compressed and the higher the frequency. For example, for a very fast vehicle traveling at the speed of sound; the compressions are all right on top of each other. Thus, faster speed means closer compressions and higher frequencies. Hence, option only option A must be true because X is a higher frequency and so it must be going faster. The distance to the person will affect the volume but will not the pitch so Option B is not correct. Option C too is not correct because It doesn’t matter whether you are speeding up or slowing down, it only matters who is going faster. For example, from option c concept, if truck X was going 10 m/h and speeding up while truck Y was going 50 mph and slowing down, it would not meet the requirement that X has a higher frequency because only actual speed matters, not what is happening to that speed. Thus only option A is the correct answer
