In a real system of levers, wheel or pulleys, the AMA (actual mechanical advantage) is less than the IMA (ideal mechanical advantage) because of the presence of friction.
In fact, the IMA and the AMA of a machine are defined as the ratio between the output force (the load) and the input force (the effort):

however, the difference is that the IMA does not take into account the presence of frictions, while the AMA does. As a result, the output force in the AMA is less than the output force in the IMA (because some energy is dissipated due to friction), and the AMA is less than the IMA.
Answer:
The time taken for the race is 17.20 s.
Explanation:
It is given in the problem that a 62.0 kg sprinter starts a race with an acceleration of 1.44 meter per second square.The initial speed of the sprinter is zero as it starts from the rest.
Calculate the final speed of the sprinter.
The expression for the equation of the motion is as follows;

Here, u is the initial speed, v is the final speed, a is the acceleration and s is the distance.
Put u= 0, s=30 m and
.


Calculate time taken to cover 30 m distance.
The expression for the equation of motion is as follows;

Put u= 0, s=30 m and
.

t=6.45 s
Calculate the time taken to complete his race.
T= t+t'
Here, t is the time taken to cover 30 m distance and t' is the time taken to cover 100 m distance.

Put s= 30 m,
and s'= 100 m.

T= 17.20 s
Therefore, the time taken for the race is 17.20 s.
Answer and Explanation:
The Sun is the main source of energy on the earth if there will be no availability of Sun energy then life is impossible om the earth besides this the Sun warms our planet. The heating of ocean and atmosphere is mainly sue to Sun energy .Sun has also a great impact on the weather we can say that Sun is weather deciding on the earth our climate is totally dependent on the how much energy we got in form of radiation from earth.
Vol of sphere = 4/3 pi r^2.density of sphere = mass/volume.mass = densityxvolumesphere 1. mass = density x 4/3 pi 4.5^2sphere 2 5mass = density x 4/3 pi r^25=4/3 pi r^2 divided by 4/3 pi 4.5^25=r^2 divided by 4.5^25x4.5^2=r^2root(5x4.5^2)=r4.5 root 5 = r