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3 years ago

10

What is the potential energy, if abody of mass 250 kg is at a height of 30metre?

1 answer:

stepan [7]3 years ago

5 0

PE = (250) (30) (9.81) = 73575J
I used to use 9.81 as acceleration due to gravity. The answer might be different from what you expect

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3 years ago

Read 2 more answers

Neglecting friction, of a pendulum bob has 100 joules of kinetic energy at the bottom of its swing, how much potential energy do

galben [10]

100 joule of kinetic energy

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3 years ago

A heavy rope, 80 ft long and weighing 32 lbs, hangs over the edge of a building 100 ft high. how much work w is done in pulling

allochka39001 [22]

The first thing you should know for this case is that work is defined as the product of force by the distance traveled in the direction of force.
We have then:
W = Fd
The distance varies, so we must integrate:
from 0 to 20:
W = ∫F (x) dx
W = ∫32xdx
W = 32∫xdx
W = 32 (x ^ 2/2) = (16) (20 ^ 2) = 6400 ft * lbs
answer:
6400 ft * lbs is work done pulling the rope up 20 ft

6 0

3 years ago

What is the mass of a child if the force of gravity on the child's body is 100 N?

MA_775_DIABLO [31]

Gravity is 9.81m/s^2 on earth F=m×g
100N=(x)kg×9.81m/s^2
x=10.19kg or more than 22lbs

5 0

3 years ago

The tub of a washer goes into its spin-dry cycle, starting from rest and reaching an angular speed of 5.0 rev/s in 9.0 s. At thi

sertanlavr [38]

Answer

given,

angular speed of the tub = 5 rev/s

time = 9 s

he tub slows to rest = 15.0 s

the angular acceleration

$\omega_f - \omega_i = \alpha t$

$\alpha = \dfrac{5-0}{9}$

$\alpha = 0.556 rev/s^2$

angular displacement

$\theta_1 = \omega_i \ t + \dfrac{1}{2}\alpha t^2$

$\theta_1 = \dfrac{1}{2}\times 0.556 \times 9^2$

$\theta_1 = 22.52 rev$

$\theta_1 = 23 rev$

case 2

now,

$\omega_i = 5 rev/s$

$\omega_f = 0 rev/s$

time = 15 s

the angular acceleration

$\omega_f - \omega_i = \alpha t$

$\alpha = \dfrac{0-5}{15}$

$v\alpha =-0.333 rev/s^2$

angular displacement

$\theta_2 = \omega_i \ t + \dfrac{1}{2}\alpha t^2$

$\theta_2 =5\times 15 -\dfrac{1}{2}\times 0.333 \times 15^2$

$\theta_2 = 37.875 rev$

$\theta_2 =38 rev$

total revolution in 24 s

= 23 + 38

= 62 revolution

8 0

3 years ago