Answer:
a. negative
b. zero
Explanation:
work is the change in the energy of a system due to external forces
work is done when a force moves a load through a distance in the direction of the force
The work done by a force on a system is positive when the force and the force displacement point in the same direction and negative when they point in opposite directions
in the scenario we are considering in the question, the force (the hand) moves the block vertically upwards but the displacement of the block reduces (in the opposite direction) since it decelerates. as such the work done by gravity on the block is negative.
the work done on the block is zero if the system consists of the block and the earth because there is no gravitational force exerted on the system
Answer:
The telescope can gather light 1600 times more than the human eyes can!
Explanation:
The light gathering ability of an optical element is directly proportional to its area of opening.
So, in comparing the light gathering abilities for two objects, it is just the ratio of their area of opening.
Let the diameter of the telescope be D = 1 m
And the diameter of the human eyes be d = 2.5 cm = 0.025 m
Light gathering ability of the telescope compared to the eyes = D² ÷ d²
= (D²/d²) = (1²/0.025²) = 1600 times.
The telescope can gather light 1600 times more than the human eyes can!
Hope this Helps!!!
Answer:
Angle of ray makes with the vertical is 62.1 degree
Explanation:
As per the ray diagram we know that the angle of incidence on oil brine interface will be given as
now by Snell'a law at that interface we have
now we will have
now this is the angle of incidence for oil air interface
so now again by Snell's law we will have
