Answer:
Robert Hooke
Was the first to use the word "cell"
Observed cork cells
Anton van Leeuwenhoek
Observed "animalcules"
Used polished lens
.
Explanation:
Anton van Leeuwenhoek is known as father of microbiology. He is credited to improve the quality of lens in microscope. His first observation of organisms called animalcules.
He is credited to have build microscope that could get magnified by 200 times. He used word animalcules for small organisms from pond water when first observed in microscope. He discovered protozoa and named it animalcules".
Robert Hooke is famed for discovering cell from a cork of plant. He observed a compartment or honey comb like divisions when observed these cork cells under the microscope and named it cell. He was only able to see the cell wall as the cork cells are dead cells.
Answer: The velocity at different marked time points are given as
t1 = -
t2 = +
t3 = +
t4 = -
t5 = 0
Explanation:
The slope of the tangent of the curve indicates the instantaneous velocity. So if the slope of the tangent is positive, that Is, the tangent makes a positive angle (above the horizontal axis) with the horizontal
axis, then the velocity at this point is positive, and if the slope of the tangent is negative, that is the tangent makes a negative angle with the horizontal axis (below the horizontal axis), then the velocity at this point is negative.
When the tangent of the line is parallel to the horizontal axis, the velocity is 0.
From the position-time graph attached, the sign on the instantaneous velocity for each time marked on the graph is given below
t1 = -
t2 = +
t3 = +
t4 = -
t5 = 0
QED!
Answer: Technician B
Explanation: A valve overlap occurs when both the exhaust valve and the inlet valve are open at the same time.
It is also seen as the number of degrees at which both the inlet and exhaust valves are open.
Valve overlap helps in boosting the efficiency of the engine by taking advantage of the expelled pressure from the exhaust.
It is expressed mathematically in degrees of shaft rotation.
So, Technician B is very correct.
<h2>
Answers:</h2>
-The first direct detection of gravitational waves came in 2015
-The existence of gravitational waves is predicted by Einstein's general theory of relativity
-Gravitational waves carry energy away from their sources of emission
<h2>
Explanation:</h2>
Gravitational waves were discovered (theoretically) by Albert Einstein in 1916 and "observed" for the first time in direct form in 2015 (although the results were published in 2016).
These gravitational waves are fluctuations or disturbances of space-time produced by a massive accelerated body, modifying the distances and the dimensions of objects in an imperceptible way.
In this context, an excellent example is the system of two neutron stars that orbit high speeds, producing a deformation that propagates like a wave,<u> in the same way as when a stone is thrown into the water</u>. So, in this sense, gravitational waves carry energy away from their sources
.
Therefore, the correct options are D, E and F.
