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3 years ago

How much work is done by gravity when a pine cone (of mass 50g) falls from the top of a tree, 9 m high?

Physics

1 answer:

Ksenya-84 [330]3 years ago

5 0

4.5 Joules. I think it'd be 4.41, but when you round it, it's 4.5.

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A mechanic needs to replace the motor for a merry-go-round. The merry-go-round should accelerate from rest to 1.5 rad/s in 7.0 s

marta [7]

Answer

given,

initial speed of merry-go-round = 0 rad/s

final speed of merry-go-round = 1.5 rad/s

time = 7 s

Radius of the disk = 6 m

Mass of the merry-go-round = 25000 Kg

Moment of inertia of the disk

$I = \dfrac{1}{2}MR^2$

$I = \dfrac{1}{2}\times 25000\times 6^2$

I = 450000 kg.m²

angular acceleration

$\alpha = \dfrac{\omega_f-\omega_0}{t}$

$\alpha = \dfrac{1.5-0}{7}$

$\alpha =0.214\ rad/s^2$

we know,

$\tau= I \alpha$

$\tau= 450000\times 0.214$

$\tau=96300\ N.m$

8 0

3 years ago

Two identical resistors are connected first in series and second in parallel. The equivalent resistances of the two types of con

trasher [3.6K]

Answer:

$\frac{R_{s} }{R_{p} } =\frac{R_{1} }{R_{2} }+\frac{R_{2} }{R_{1} } +2$

Explanation:

We have series and parallel combination of two resisters $R_{1}$ and $R_{2}$ .

Series combination is

$R_{s}= R_{1}+R_{2}$ and Parallel is $R_{p} = (\frac{1}{R_{1}}+\frac{1}{R_{2}} )^-1$

Now dividing series equivalent resistance by parallel resistance gives us

$\frac{R_{s} }{R_{p} } =\frac{R_{1} }{R_{2} }+\frac{R_{2} }{R_{1} } +2$ .

Note! series Combination is simply superposition of two elements (resisters in this case ) in a circuit.

4 0

3 years ago

8-30-2018 what phase change occurs as the substance at 0 degree c has its pressure dropped from 0.50 at to 0.25 atm

madam [21]

Answer:

at T = 0ºC the change of state is from the solid state to the gaseous state

Explanation:

In this exercise we are asked about the changes of state, from the data we will assume that the material is water.

Water can exist in three solid states, liquid and gas, in a graph of pressure ℗ against temperature (T) there is a point called triple at T = 0.01ºC, below this point the curve has two states at high pressure solid and low pressure gas.

As a result of the previous ones at T = 0ºC the change of state is from the solid state to the gaseous state

7 0

3 years ago

MathPhys Help pls Tysm

HACTEHA [7]

Answer:

8.75

Explanation:

First, find the force of friction.

Kinetic energy = work done by friction

½ mv² = Fd

½ (3.9 kg) (2.9 m/s)² = F (1.4 m)

F = 11.7 N

Next, find the distance at the new velocity.

Kinetic energy = work done by friction

½ mv² = Fd

½ (3.9 kg) (2.5 × 2.9 m/s)² = (11.7 N) d

d = 8.75 m

3 0

3 years ago

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VERY EASY QUESTION!!!!!! 20 POINTS!!!!!!!!

slamgirl [31]

C. at a science fair

4 0

3 years ago

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