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Sophie [7]
3 years ago
15

What do you understand by ?efficiency of a machine is 70%​

Physics
1 answer:
tatuchka [14]3 years ago
8 0

Explanation:

The efficiency of a machine is 70% means 30% of the applied force is wasted in overcoming friction and 70% of the applied force is used to do the work

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A 70 kg object strikes the ground with 2500 J of KE after falling freely from rest. How far above the ground was the object when
Kitty [74]

Answer:

3.64 m

Explanation:

m = Mass of object = 70 kg

Kinetic energy of the object = 2500 J

g = Acceleration due to gravity = 9.81\ \text{m/s}^2

h = Height from which the object is dropped

Kinetic energy is given by

\dfrac{1}{2}mv^2=2500\\\Rightarrow v^2=\dfrac{2\times 2500}{70}

From conservation of energy we get kinetic energy equal to potential energy.

\dfrac{1}{2}mv^2=mgh\\\Rightarrow h=\dfrac{1}{2g}v^2\\\Rightarrow h=\dfrac{1}{2\times 9.81}\times \dfrac{2\times 2500}{70}\\\Rightarrow h=3.64\ \text{m}

The object was released from a height of 3.64 m.

6 0
3 years ago
The table shows the potential energy and kinetic energy of a skier at two different positions on a hill.
Serggg [28]

Answer:

30,000 units, because total energy remains unchanged

6 0
3 years ago
Read 2 more answers
A resin tube and a PVC rod are both rubbed against styrofoam. Do
Ivan

The concepts of electrostatics allow us to find the result for the question about the electric forces in the two tubes is:

  • The tubes are attracted by having charges of different signs.

<h3>Electrostatics</h3>

Electrostatics studies the transfer of charge between bodies when they rub together, in generating the charges of the insulating bodies they are not mobile, so to transfer them from one body to another they must be in contact.

The force electric between charges is of two types:

  • Attractive. If the charges are of different signs.
  • Repulsive.  If  the charges are of the same sign.

The transferred charge depends on the bodies involved in the tables showns that the resin is positively charged when rubbed, the PVC acquires very little charge and polystyrene acquires a negative charge due to rubbing.

They indicate that the resin is rubbed with polystyrene, therefore the resin must acquire a positive charge and the polystyrene a negative charge.

Then the PVC is rubbed with the polystyrene, which initially we will assume neutral, the PVC does not acquire a charge and the polystyrenes acquires a negative charge, if the polystyrene is isolated from the ground, it shares this negative charge with the PVC, therefore the two materials remain with half of the negative charge.

Finally, we bring the resin, which is positively charged, closer to the PVC, which has a slight negative charge, therefore the two bodies must attract each other.

In conclusion using the concepts of electrostatics we can find the result for the question about the electric forces in the two tubes is:

  • The tubes are attracted by having charges of different signs.

Learn more about electrostatics here: brainly.com/question/17692887

6 0
3 years ago
A projectile is fired with a velocity of 22 m/s at an angle of 25°. What is the vertical component of the velocity?
7nadin3 [17]

Answer:

Vertical component of velocity is 9.29 m/s

Explanation:

Given that,

Velocity of projection of a projectile, v = 22 m/s

It is fired at an angle of 22°

The horizontal component of velocity is v cosθ

The vertical component of velocity is v sinθ

So, vertical component is given by :

v_y=v\ sin(25)

v_y=22\ m/s\times\ sin(25)

v_y=9.29\ m/s

Hence, the vertical component of the velocity is 9.29 m/s

3 0
4 years ago
The plate tectonic theory was initially rejected. TRUE. FALSE?
Sveta_85 [38]
This is true.
Hope this helps
3 0
3 years ago
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