The true statements about magnetic fields and forces will be A,D and E.
<h3>What is a magnet?</h3>
An iron piece,alloy, or other substance with its constituent atoms arranged in such a way that it shows magnetism qualities,
The function of the magnet is attracting other iron-containing objects or aligning itself in a magnetic field.
There are two poles of the magnet;
1. North Pole.
2. South Pole.
The same poles repel each other, while the opposite poles attract each other. In a sense, south-south and north-north repel. While the north-south and the south-north attract each other.
The correct statements are;
(A). The north pole attracts the south pole of a magnet.
(D)Forces caused by magnetic fields are weaker farther from the magnet.
(E)Magnetic forces can act on an object even if the object isn't touching the magnet.
Hence, the true statements about magnetic fields and forces will be A,D and E.
To learn more about the magnet, refer to the link;
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It hardens because you are pressing it against something.
Answer: 50.7 J
Explanation:
Given
mass of lion is 
The initial speed of the lion is 
increased speed of lion is 
Initially, its kinetic energy is 
Final kinetic energy 
work did by lion after speed up is 
![\Rightarrow W=\dfrac{1}{2}\times 2.6[8^2-5^2]\\\\\Rightarrow W=1.3\times [39]=50.7\ J](https://tex.z-dn.net/?f=%5CRightarrow%20W%3D%5Cdfrac%7B1%7D%7B2%7D%5Ctimes%202.6%5B8%5E2-5%5E2%5D%5C%5C%5C%5C%5CRightarrow%20W%3D1.3%5Ctimes%20%5B39%5D%3D50.7%5C%20J)
The work done on the backpack by the student applies 80 N of force to lift the backpack 1.5 m is 120J.
<h3>How to calculate work done?</h3>
Work done is a measure of energy expended in moving an object; most commonly, force times distance.
It is said that no work is done if the object does not move, hence, the work done on an object can be calculated as follows:
Work done = Force × Distance
According to this question, a student carries a very heavy backpack and to lift the backpack off the ground, the student must apply 80 N of force to lift the backpack 1.5 m.
Work done = 80N × 1.5m
Work done = 120J
Therefore, the work done on the backpack by the student applies 80 N of force to lift the backpack 1.5 m is 120J.
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a) In this case the forces are the centrifugal force Fcp,
which is directed horizontally toward the wall; the force of static friction Ff
with the wall, directed upward; the normal force Fn by the wall, which is
directed away the wall; the force of gravity Fg, directed downwards. Then we
have that the horizontal forces are all equal in magnitude; similarly the
vertical forces are also all equal in magnitude.
b) The minimum coefficient s occurs when force of gravity
is equals the max friction force, that is
Fg = Ff,max
m g = s Fn
Also, the normal force has equal magnitude to the
centrifugal force:
m g = s Fcp
m g = s m w^2 r
g = s w^2 r
s = g / (r w^2)
With values: g = 9.81 m/s^2; r = 2.5 m; and w = 2pi *
0.60 = 3.77 rad/s; we find
s = 9.81 / (2.5 * 3.77^2) = 0.276
