Answer:
Sum of the forces will be equal to 3.479 N
Explanation:
We have given two same forces are oriented at an angle of 38°
Magnitude of each force is given 
We have to find the sum of the forces
Sum of the forces will be equal to

So sum of the forces will be equal to 
So sum of the force will be equal to 3.479 N
The work done by Joe is 0 J.
<u>Explanation</u>:
When a force is applied to an object, there will be a movement because of the applied force to a certain distance. This transfer of energy when a force is applied to an object that tends to move the object is known as work done.
The energy is transferred from one state to another and the stored energy is equal to the work done.
W = F . D
where F represents the force in newton,
D represents the distance or displacement of an object.
Force = 0 N, D = 20 cm = 0.20 m
W = 0
0.20 = 0 J.
Hence the work done by Joe is 0 J.
the relation that relates the speed of wave, frequency of wave and wavelength is given as
wavelength = 
the speed of wave in a medium remains constant. hence the wavelength is inversely related to the frequency of wave.
that means, as the frequency is increased, the wavelength decreases and vice versa.
hence the correct choice is
B decreases
Answer:
The work done by gravity is 784 J.
Explanation:
Given:
Mass of the block is, 
Height to which it is raised is, 
Acceleration due to gravity is, 
Now, work done by gravity is equal to the product of force of gravity and the distance moved in the direction of gravity. So,

Force of gravity is given as the product of mass and acceleration due to gravity.
. Now,

Therefore, the work done by gravity is 784 J.
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