Answer:
Copernicus discoveres thr heliocentric theory. It was previously believed that everything orbited the Earth, geocentric theory. Copernicus said he believed the Earth and everything else orbited around the Sun.
Answer:
The required work done is 
Explanation:
Consider 'F' is the applied force on the crate and 'f' be the force created by friction. According to the figure if '
' be the coefficient of friction, then

where 'M', 'N' and 'g' are the mass of the crate, the normal force aced upon the block and the acceleration due to gravity respectively.
Since the application of force by the movers does not create any acceleration to the block, we can write

So the work done (W) in moving the crate by a distance s = 10.6 m is

<u>Answer:</u>
<em>Instantaneous velocity is equal to speed of the object at that particular instant.</em>
<u>Explanation:</u>
Instantaneous velocity is the velocity of the object at that particular instant. It is also equal to speed of the object at that instant. It can be calculated by drawing a tangent to the position-time graph at that point and finding the tangent’s slope.
The first option ‘The ratio of change in position to the time interval during that change’ gives the average velocity of an object and not speed. Similarly the second option ‘the absolute value of the slope of position time graph’ gives the average speed.