Answer:t=0.81 s
Explanation:
Given
Penguin slides down with constant velocity of 3.57 m/s
as the Penguin Slides with constant velocity therefore
is zero on Penguin

friction Force

coefficient of Kinetic friction



after reaching on floor final velocity of penguin will be zero after time t
thus

here 
(deceleration)



Answer:
Explanation:
If an object is moving, it is said to have kinetic energy (KE). Potential energy (PE) is energy that is "stored" because of the position and/or arrangement of the object. The classic example of potential energy is to pick up a brick. When it's on the ground, the brick had a certain amount of energy.
Answer:
<em>h = 20 m</em>
Explanation:
<u>Gravitational Potential Energy</u>
Gravitational potential energy (GPE) is the energy stored in an object due to its vertical position or height in a gravitational field.
It can be calculated with the equation:
U=m.g.h
Where m is the mass of the object, h is the height with respect to a fixed reference, and g is the acceleration of gravity or
.
The weight of an object of mass m is:
W = m.g
Thus, the GPE is:
U=W.h
Solving for h:

The weight of the owl is W=40 N and its GPE is U=800 J.

h = 20 m
The most probable reason why the magnets won't stick on the refrigerator is that the body of the refrigerator and the magnets have like poles. If both have negative or both have positive poles facing each other, they will repel. In principle, magnets are attracted to opposite poles and like poles repel.
Answer:
1) Mass that needs to be converted at 100% efficiency is 0.3504 kg
2) Mass that needs to be converted at 30% efficiency is 1.168 kg
Explanation:
By the principle of mass energy equivalence we have

where,
'E' is the energy produced
'm' is the mass consumed
'c' is the velocity of light in free space
Now the energy produced by the reactor in 1 year equals

Thus the mass that is covertred at 100% efficiency is

Part 2)
At 30% efficiency the mass converted equals
