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3 years ago

An 85-kg refrigerator is located on the 70th floor of a skyscraper (4km above the ground ) what is the potential energy

1 answer:

7 0

Potential energy can be calculated using the following rule:
potential energy = mgh where:
m is the mass = 85 kg
g is the acceleration due to gravity = 9.8 m/sec^2
h is the height = 4 km = 4000 meters

Substitute in the above equation to get the potential energy as follows:
Potential energy = 85*9.8*4000 = 3332000 joules

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Planet X has three times the free-fall acceleration of Earth.

serious [3.7K]

Answer:

a) The ball goes one-third times higher on X

b) The ball goes three times higher on X.

Explanation:

As the initial velocity is the same than on Earth, but the free-fall acceleration is three times larger, this means that the only net force acting on the ball (gravity) will be three times larger, so it is clear that the ball will reach to a lower height, as it will slowed down more quickly.
Kinematically, as we know that the speed becomes zero when the ball reaches to the maximum height, we can use the following kinematic equation:

$v_{f} ^{2} - v_{o}^{2} = 2* \Delta h* g$

since vf = 0, solving for Δh, we have:

$\Delta h = h_{max} =\frac{v_{o} ^{2}}{2*g} (1)$

if v₀ₓ = v₀E, and gₓ = 3*gE, replacing in (1), we get:

Δhₓ = 1/3 * ΔhE

which confirms our intuitive reasoning.

Now, if the initial velocity is three times larger than the one on Earth, even the acceleration due to gravity is three times larger, we conclude that the ball will go higher than on Earth.
We can use the same kinematic equation as in (1) replacing Vox by 3*VoE, as follows:

$\Delta h = h_{max} =\frac{(3*v_{o}) ^{2}}{2*3*g} (2)$

Replacing the right side of (1) in (2), we get:

Δhx = 3* ΔhE

which confirms our intuitive reasoning also.

7 0

3 years ago

A marble is dropped off the top of a building. Find it's velocity and how far below to its dropping point for the first 10 secon

Yuri [45]

consider the motion in y-direction

v₀ = initial velocity = 0 m/s

a = acceleration = g = - 9.8 m/s²

t = time

v = final velocity at any time "t"

velocity at any time is given as

v = v₀ + at

v = 0 + (- 9.8) t

v = (- 9.8) t

so at t = 1 , v = (- 9.8) (1) = - 9.8 m/s

at t = 2 , v = (- 9.8) (2) = - 19.6 m/s

at t = 3 , v = (- 9.8) (3) = - 29.4 m/s and so on

Y₀ = initial position where the marble was dropped from = 0 m

Y = final position at any time "t"

final position at any time "t" is given as

Y = Y₀ + v₀ t + (0.5) a t²

Y = 0 + (0) t + (0.5) (-9.8) t²

Y = - 4.9 t²

at t = 1 , Y = - 4.9 (1)² = - 4.9 m

at t = 2 , Y = - 4.9 (2)² = - 19.6 m

at t = 3 , Y = - 4.9 (3)² = - 44.1 m

and So on

6 0

3 years ago

A child and sled with a combined mass of 58.0 kg slide down a frictionless slope. If the sled starts from rest and has a speed o

erma4kov [3.2K]

Answer:

The height is $h = 0.5224 \ m$

Explanation:

From the question we are told that

The combined mass of the child and the sled is $m = 58.0 \ kg$

The speed of the sled is $u = 3.20 \ m/s$

Generally applying SOHCAHTOA on the slope which the combined mass is down from

Here the length of the slope(L) where the combined mass slides through is the hypotenuses

while the height(h) of the height of the slope is the opposite

Hence from SOHCAHTOA

$sin (\theta) = \frac{h}{L}$

=> $Lsin(\theta) = h$

Generally from the kinematic equation we have that

$v^2 = u^2 + 2aL$

Here the u is the initial velocity of the combined mass which is zero since it started from rest

and a is the acceleration of the combined mass which is mathematically evaluated as

$a = g * sin (\theta )$

$v^2 = u^2 + 2 * g * sin (\theta )L$

=> $2Lsin(\theta ) = \frac{v^2 - u^2 }{g}$

=> $h = \frac{ v^2 - u^2}{2g}$

=> $h = \frac{ 3.20^2 - 0^2}{2 * 9.8 }$

=> $h = 0.5224 \ m$

6 0

3 years ago

What is the meaning of s in heat energy?

ValentinkaMS [17]

Answer:Specific heat is the amount of heat required to raise one gram of any substance one degree Celsius or Kelvin. The formula for specific heat is the amount of heat absorbed or released = mass x specific heat x change in temperature.

Explanation:

HOPE IT HELP

6 0

3 years ago

Where in the dive above would kinetic energy and potential energy be equal?

Diano4ka-milaya [45]

Answer: The sum of an object's potential and kinetic energies is called the object's mechanical energy. As an object falls its potential energy decreases, while its kinetic energy increases. The decrease in potential energy is exactly equal to the increase in kinetic energy.

6 0

3 years ago