Question

Lamar Gant, U.S. powerlifting star, became the first man to deadlift five times his own body weight in 1985. Deadlifting involves raising a loaded barbell from the floor to a position above the head with outstretched arms. Determine the work done by Lamar in deadlifting 300 kg to a height of 0.90 m above the ground (W=Fd).

a. 270 J
b. 2646 J
c. 333 J
d. 3.00X10-3 J

Answer 1

Answer:

(b) 2646 J

Explanation:

Earth's gravitational field exerts gravitational force that has direction towards the center of earth, we know that where there is force there is work.

Work by definition is given by.

$W = F.d$  here in this case  $F$ is force because of gravity which has the magnitude of $F_{g} =mg$.

We are making an assumption that we are not too high to change the value of $g.$

And $d = h = 0.9m$.

Putting or substituting these values in the equation of work that i introduced above gives.

$W = mgh = 300kg*9.8*0.9m=2646J$

and it is Option (b).

Note!  units will always be joules for work, joule by definition is Nm.

and $g =9.8m/s^2$.

 

Answer 2

The work done by Lamar in deadlifting 300 kg to a height of 0.90 m above the ground is 2646 Joules

Work is the amount of energy exerted in other to perform an activity. Work is the product of force and displacement. It is given by:

Work = force * displacement

Given that the mass = 300 kg, height = 0.9 m, acceleration due to gravity (g) = 9.81 m/s². Hence:

Work = mass * acceleration due to gravity * height

Work = 300 * 9.81 * 0.9 = 2646 Joules

The work done by Lamar in deadlifting 300 kg to a height of 0.90 m above the ground is 2646 Joules

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