Calculating Velocity of a Man Jumping from 90m Building | Physics Question

[YesINeedhelp]

IF a man jumps off a building that is 90 m high, and gravity is 9.8 m/s, and he weighs 80 kg, then what will his velocity be just as he hits the ground?

 

[warmfire540]

just use the equation

vf^2=vi^2 +2ax
vf^2=0+2(9.8)(90)
vf^2=1764
v=42 m/s

weight is irrelevant

 

[Moetasim]

I would approach this question by using the principles of physics and the equations of motion. The first step would be to determine the acceleration due to gravity, which is given as 9.8 m/s^2. This value is constant and acts on the man throughout his fall.

Next, I would use the equation for calculating velocity, which is v = u + at, where v is the final velocity, u is the initial velocity (which is 0 in this case), a is the acceleration, and t is the time. In this scenario, we are interested in the final velocity just as the man hits the ground, so we can rearrange the equation to solve for v:

v = u + at
v = 0 + (9.8 m/s^2)(t)

To determine the time, we can use the equation for calculating time, t = √(2h/g), where h is the height of the building and g is the acceleration due to gravity. Plugging in the values given in the question, we get:

t = √(2*90m/9.8m/s^2)
t = 4.29 seconds

Now, we can plug in the value of time into the equation for velocity:

v = (9.8 m/s^2)(4.29 s)
v = 42.12 m/s

Therefore, just as the man hits the ground, his velocity will be approximately 42.12 m/s. It is important to note that this calculation does not take into account air resistance, which can affect the velocity of the man. Additionally, the weight of the man was not necessary for this calculation as it does not affect the acceleration due to gravity.