A person picking up a box from the ground
Explanation:
Work is defined as measure of energy transfer that occurs when an object is moved from one place to another by an external force at least part of which is applied in the direction of the displacement. Basically, work implies activity whether an activity done by body, of mind, of a machine, or of a natural force. In picking up a box from the ground there is no movement of person from one palce to another, hence no work done by him. Work is done only when he picks the box and moves from one point to another while carrying it.
Answer:
D
Explanation:
The negative feedback is responsible for maintaining equilibrium (stability) in a system as it lessens effects, which is contrary to positive feedback which increases reaction and moves a system further away from equilibrium (stability), It does so by amplifying the effects of a product or event and occurs when something needs to happen quickly. e.g
- Insulin lowers down blood sugar levels, so when the body detects that it has too much sugar, the pancreas is prompted to release insulin and only stops when balance is achieved; hence, negative feedback.
- When there is a tear on the skin, a chemical is released. This chemical causes platelets in the blood to activate, hence they release a chemical which signals more platelets to activate, until the wound is clotted, positive feedback.
Answer: The correct answer is Diffraction.
Explanation:
Diffraction is the phenomenon in which a beam of light will get bend when it passes through a narrow aperture. It is accompanied by the interference between the wave form produced.
Consider a wave approaching a barrier with a small hole. The diffraction will occur when the wave passes through the hole. There is a bending of light as it passes through the edge of the object or through the hole.
The amount of bending light depends on the relative size of wavelength of the light in comparison to the size of the aperture.
Therefore, the correct answer is Diffraction.
Answer:
308 m/s
Explanation:
In a closed tube, the length of the tube (L) is related to the wavelength of the standing wave (
) by the relationship
In this problem, the length of the tube is L=20 cm=0.20 m, so we can find the wavelength of the standing wave:
And no we can find the speed of the sound wave by using the following equation:
where 
is the frequency of the wave. So, we find
