Speed is the rate at which something covers a distance; velocity is the same but it takes into account whether it goes forwards or backwards; and acceleration is the rate of an increase in speed.
Answer:
400 kilogram
Explanation:
Force exerted is directly proportional to the mass of an object.
F=ma where m is mass and a is acceleration. Taking uniform acceleration on all objects then the larger the mass the higher the force and vice versa. Theredore, among the masses given, 400 kilograms is the largest hence it exerts the largest force at the bottom
Answer:

Explanation:
As we know that the angular acceleration of the wheel due to friction is constant
so we can use kinematics

so we have



now time required to completely stop the wheel is given as



now time required to stop the wheel is given as


It really all depends weather the temperature
Answer: A, C and D
Explanation:
Interference occurs when two waves superimpose to form a wave having a smaller or larger amplitude.
Constructive interference is said to occur when two waves superimpose to produce a wave having larger amplitude. It occurs for the waves having phase difference of multiple of 2π. On the other hand, destructive interference occurs for the waves having phase difference π, 3π, ..and so on.
In the given picture, the bright regions represent constructive interference where as the dark ones between them represent destructive interference. Thus, the correct letters representing constructive interference are: A, C and D.