Answer:
Acceleration, 
Explanation:
Given that,
The plane is at rest initially, u = 0
Final speed of the plane, v = 72.2 m/s
Time, t = 29 s
We need to find the average acceleration for the plane. It can be calculated as :
So, the average acceleration for the plane is 
. Hence, this is the required solution.
Solution :
We know that :
Formula for Gravitational force is given by :
where, G is the gravitational constant
M is the mass of the bigger body
m is the mass of the smaller body
r is the distance between the two bodies.
And the formula for the centripetal force is given by :
where, m is the mass of the rotating body
v is the velocity
r is the radius of rotation of the body.
We know that mathematically, the gravitational force is equal to the centripetal force of the body.
Therefore,
Hence derived.
When the force of air resistance on the skydiver
is equal to the skydiver's weight.
Answer:
When a bee stings, it injects methanoic acid into the skin which causes immense pain and irritation. Rubbing of baking soda on the sting area gives relief because, being alkaline in nature, baking soda neutralizes the effect of methanoic acid and gives relief.
Use of fossil fuels has not lead to increased use of wood as heat source.
Answer: Option D
<u>Explanation:</u>
Fossil fuels are materials required to generate heat or thermal energy and they are obtained by the decomposed remains of plants, animals and human beings. But the fossil fuels generally present in the bottom layer of earth crust or sometimes mixed with stones or rock minerals. So we need to highly energetic drilling devices to extract the fossil fuels.
Thus, before the introduction of fossil fuels, wood is used as the igniting source for heat energy. But the entry of fossil fuels have reduced the use of wood as igniting source in cooking, burning etc.
Thus, the use of fossil fuels have increased exchange of culture and ideas as fuels are mostly imported from other nations, it lead to development of faster transportation methods and increased the availability of products including heat, plastics and medicine. But similarly, the use of fossil fuels have not increased the use of wood as heat source, instead it decreased the use of wood as heat source.
