Explanation:
Echoes occur due to the reflection of sound from any obstacle, but not all the reflected sound waves lead to the phenomenon of echo. For the echo to be heard it actually depends upon the human perception as well, human ears can encounter the difference between the sound wave directly form the source and the reflected sound waves only if there is a minimum time gap of one-tenth of a second. For this time gap in the atmosphere at normal temperature and pressure the obstacle must be at least 7 meters away from the sound source.
Answer:
Option A
Lowering the amount of reactants
Explanation:
To reduce the rate of chemical reaction, one can reduce temperature or surface area. The addition of catalysts increases rate of reaction but decreasing the amount of reactants decreases rate of reaction. Therefore, from the choices provided, choice A is correct.
Answer:
Part a)
Part b)
Explanation:
Part a)
For force conditions of two blocks we will have
now from above equations we have
now we know that
now from above equation we have
Part b)
When heavier block is removed and F = 908 N is applied at the end of the string then we have
The cheetah can run 28,25 km
