Answer:
The speed of man before he hits the ground is <u>23.35 m/s</u>
Explanation:
We know that:
Weight of Man - Force of Friction = Unbalanced Force
but, from Newton's 2nd Law of Motion:
unbalanced force = ma
Therefore,
W - F = ma
a = (W - F)/m
a = (mg - F)/m
where,
m = 81 kg
g = 9.8 m/s²
F = 103 N
a = [(81 kg)(9.8 m/s²) - 103 N]/81 kg
a = 8.52 m/s²
using 3rd equation of motion:
Vf² - Vi² = 2ah
here,
Vi = initial velocity = 0 m/s
Vf = Final Velocity before he hits ground = ?
Vf² - 0² = 2(8.52 m/s²)(32 m)
Vf = √545.28 m²/s²
<u>Vf = 23.35 m/s</u>
These are all followed and prompted by a question
-- Use power when you're dealing with an amount of energy
AND the time it took. Because ...
Power =
(amount of work done or energy moved)
divided by
(time to do the work or move the energy from one place to another).
-- Use an energy equation when you have to figure out an amount of energy.
It would come up in situations like this:
. . . . . how much work is done (work is energy)
. . . . . energy needed to melt some amount of ice
. . . . . energy needed to boil some amount of water
-- Use an efficiency equation when you're dealing with
. . . . . the amount of work, or energy, or power going in
. . . . . AND the amount of work, or energy, or power coming out.
Velocity = dy/dx = first derivative of f(x) evaluated at given point. It is the change in position over time.
speed = absolute value of velocity (square your velocity and then square root it)
acceleration = d^2y/dx^2 = second derivative of f(x) evaluated at a given point. It is also the first derivative of your velocity function, or the change in velocity over time.
Both velocity and acceleration are vectors, that is, they are either positive or negative in a direction. Speed is the magnitude of your velocity and has no direction: it is simply the absolute value of your velocity.
2) For multi-variable functions: f(x,y)
velocity = first partial derivative with respect to x + first partial derivative with respect to y. It is the vector sum of these two vectors.
speed = the same as it is for single variable, that is, speed is the absolute value of the velocity. However, in multi-variable functions you must square all your components and then square root it (ie: Pythagorean Theorem: sqrt(i^2+j^2+k^2), with (i,j,k) being the x,y,z, respectively).
acceleration is analogous to single variable acceleration. It is now the 2nd partial with respect to x + 2nd partial with respect to y.
<u> Focal Length of the lens is 3.846 cm.</u>
Explanation:
Image Distance ( i ) = 4 cm
Object Distance ( o ) = 100 cm
Find,
Focal length =?
Focal length of pair of glasses can be calculated as -
.............<u> ( here 1 / o it's o = object distance )</u>
<u> Focal Length of the lens is 3.846 cm.</u>