The time taken by the stone to hit the ground would be 5.12 seconds.
<h3>What are the three equations of motion?</h3>
There are three equations of motion given by Newton
The first equation is given as follows
v = u + at
the second equation is given as follows
S = ut + 1/2×a×t²
the third equation is given as follows
v² - u² = 2×a×s
Keep in mind that these calculations only apply to uniform acceleration.
As given in the problem, a stone is dropped from the helicopter which is ascending at the speed of 19.6 m/s
height(S) = 156.8 meters
initial velocity(u) = -19.6 m/s
acceleration(a) = 9.81 m/s²
By using the second equation of motion given by newton
S = ut + 1/2at²
S = 156.8m ,u= -19.6 m/s , a= 9.81 m/s² and t =? seconds
156.8= -19.6t + 9.81t²
t = 5.12 seconds
Thus, the time taken by the stone to hit the ground would be 5.12 seconds.
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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.
Answer:
Subduction is a geological process that takes place at convergent boundaries of tectonic plates where one plate moves under another and is forced to sink due to high gravitational potential energy into the mantle. Regions where this process occurs are known as subduction zones. Rates of subduction are typically measured in centimeters per year, with the average rate of convergence being approximately two to eight centimeters per year along most plate boundaries. so i believe so
Explanation:
nmw
Yes, this is an example of a force because a force is a push or pull.
Answer:
Friction
Explanation:
The key and most important external forces that allows a man to push a wheelbarrow is frictional force.
Frictional force is a force that opposes motion and will bring it to a halt.
The reason why motion is possible is due to frictional force.
Without friction, a body will move and continue in motion infinitely. No one will be able to control motion.
- Therefore, frictional force is an external force that will allow a man to push a wheelbarrow.
