Answer:
Explanation:
This is a problem based on time dilation , a theory given by Albert Einstein .
The formula of time dilation is as follows .
t₁ = 
t is time measured on the earth and t₁ is time measured by man on ship .
A ) Given t = 20 years , t₁ = ? v = .4c
=1.09 x 20
t₁= 21.82 years
B ) Given t = 5 years , t₁ = ? v = .2c
=1.02 x 5
t₁= 5.1 years
C ) Given t = 10 years , t₁ = ? v = .8c
=1.67 x 10
t₁= 16.7 years
D ) Given t = 10 years , t₁ = ? v = .4c
=1.09 x 10
t₁= 10.9 years
E ) Given t = 20 years , t₁ = ? v = .8c
=1.67 x 20
t₁= 33.4 years
The work-energy principle states that the work done by all the non-conservative forces acting on an object (or system of objects) causes a change in the total mechanical energy of the object or system.
What is the work-energy principle?
The work-energy principle states that the total work done on a system is equal to the change in kinetic energy of the system. It is given as:
W.D = ΔK.E
= K.E₁ - K.E₂
where K.E₁ is the initial kinetic energy of the system
K.E₂ is the final kinetic energy of the system
What is meant by non-conservative forces?
Non-conservative forces as the name suggests are not conserved i.e. these forces cause a loss of mechanical energy from the system. A prime example of non-conservative forces is friction.
The total mechanical energy of the system is the sum of the potential energy and kinetic energy that the system contains. This energy is conserved and follows the work-energy theorem.
Learn more about work and energy here:
<u>brainly.com/question/17290830</u>
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The collision between two objects is an example of a contact force
High frequency for the range of radio frequency electronmagnetic waves between 3 and 30 megahertz (MHz)
