The normal force acting on April as she stands on a flat surface is 705.6 N.
Normal force of the girl
Fₙ = mg
where;
- Fₙ is the normal force of the girl
- m is mass of the girl
- g is acceleration due to gravity
Fₙ = 72 x 9.8
Fₙ = 705.6 N
Thus, the normal force acting on April as she stands on a flat surface is 705.6 N.
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Answer:
a ) = 381.48 J
b )= 84.25 cm
Explanation:
Kinetic energy of the runner
= 1/2 m v²
= .5 x 66 x 3.4²
= 381.48 J
The final kinetic energy of the runner is zero .
Loss of mechanical energy
= 381.48 J
This loss in mechanical energy is due to action of frictional force .
b )
Let s be the distance of slide
deceleration due to frictional force
= μmg/m
.7 x 66 x 9.8 / 66
a = - 6.86 m s⁻¹
v² = u² - 2 a s
0 = 3.4² - 2x6.86 s
s = 3.4² / 2x6.86
= .8425 m
84.25 cm
Newton's first law states that every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force.
Keeping in mind that the conversion between calories and Joules is
we can write the conversion factor using the kilocalories:
The energy released in our problem is
so we can set a simple proportion to find its equivalent in kcal:
from which we find:
