Answer:
Work done required is 3567.2 J
Explanation:
Given :
Length of chain, l = 72 m
Mass of chain, M = 29 kg
Linear mass density of chain, μ =
=
= 0.40 kg/m
Let x be the length of the chain which lift to the top of the building.
Work done required to lift the chain is equal to the potential energy of the chain.
W = ∫μg (72 - x ) dx
Here g is acceleration due to gravity.
The limit of integration is from 0 to 14.
W = μg ( 72x - x²/2)
Substitute 0.40 kg/m for μ, 9.8 m/s² for g and 14 m for x in the above equation.
W = 
W = 3567.2 J
A force sets an object in motion when the force is multiplied by the time of its application.
Answer:
a) a = 1,865 m / s² and b) t = 8.1 s
Explanation:
a) Let's use Newton's second law to find acceleration, we can work the equation in scalar form because displacement and force have the same direction
F = m .a
a = F / m
a = 8.02 10² /4.3 10²
a = 1,865 m / s²
b) We use kinematic relationships in one dimension
vf = vo + at
vf = 0 + a t
t = vf / a
t = 15.1 / 1.865
t = 8.1 s
Answer:
3.25 seconds
Explanation:
It is given that,
A person throws a baseball from height of 7 feet with an initial vertical velocity of 50 feet per second. The equation for his motion is as follows :

Where
s is the height in feet
For the given condition, the equation becomes:

When it hits the ground, h = 0
i.e.

It is a quadratic equation, we find the value of t,
t = 3.25 seconds and t = -0.134 s
Neglecting negative value
Hence, for 3.25 seconds the baseball is in the air before it hits the ground.