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4 years ago

What are three properties that magnets have?

1 answer:

3 0

1. Magnets attract objects of iron, cobalt and nickel.
2. The force of attraction of a magnet is greater at its poles than in the middle.
3. Like poles of two magnets repel each other.

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Efficincy of simple machine is 60% what does it mean?<br>

umka2103 [35]

Explanation:

By the statement, Efficiency of a machine is 60% it is meant that 'The work output is 60% of the work input'. If you apply 100J of energy for a machine, it will be able to life load of 60 J only

7 0

3 years ago

A small block of mass M = 0.10 kg is released from rest at point 1 at a height H = 1.8 m above the bottom of a track, as shown i

Ede4ka [16]

Answer:

Explanation:

A) is not correct, because the gravitation potential energy will depend on the height the block is located at. It will be calculated with the formula:

U=mgh.

If we take the ground as a zero height reference, then on point 2 the potential energy will be:

$U_{2} = 0.10kg(9.81 m/s^{2})(0.6m)$

$U_{2}=0.59 J$

While on point 3, the potential energy will be greater.

$U_{3}=0.10kg(9.81 m/s^{2})(1.2m)$

$U_{3}=1.18 J$

B) is not the right answer because the kinetic energy will vary with the height the block is located at in the fact that the energy is conserved (this is if we don't take friction into account or air resistance) so in this case:

$U_{2}+K_{2}= U_{3}+K_{3}$

We already know the potential energy at point 2. We can calculate the kinetic energy at point 3 like this:

$K_{3} =\frac{1}{2}mv_{3}^{2}$

$K_{3} =\frac{1}{2}(0.10kg)(2.5 m/s)^{2}$

$K_{3} =0.31 J$

So the kinetic energy at point 2 is given by the equation:

$K_{2} =U_{3}-U_{2}+K_{3}$

so:

$K_{2} = (1.18J)-(0.59J)+0.31J$

$K_{2} =0.9J$

As you may see the kinetic energy at point 2 is greater than the kinetic energy at point 3.

C) Is not correct because according to the first law of thermodinamics, energy is not lost, only transformed. So, since we are not taking into account friction or any other kind of loss, then we can say that the amount of mechanical energy at point 1 is exactly the same as the mechanical energy at point 3.

D) Because of what we talked about on part C, this will be the true situation, because the mechanical energy of the block will be the same no matter theh point you measure it at.

7 0

3 years ago

A rod (length = 80 cm) with a rectangular cross section (1.5 mm × 2.0 mm) has a resistance of 0.20 Ω. What is the resistivity of

Andru [333]

Answer:

The resistivity of the material used to make the rod is ρ= 7.5 * 10⁻⁷ Ω.m

Explanation:

R= 0.2 Ω

L= 0.8 m

S= 1.5mm*2mm= 3 mm² = 3 * 10⁻⁶ m²

ρ = (R*S)/L

ρ= 7.5 * 10⁻⁷ Ω.m

7 0

3 years ago

100g converted to kg .

natka813 [3]

Answer: 0.1 kilogram

4 0

3 years ago

A 0.68 kg squirrel is resting on a branch 8 meters above the ground. What is the gravitational potential energy of a squirrel? A

ANEK [815]

Answer:

The gravitational potential energy of a squirrel is 53.312 J.

Explanation:

We have,

Mass of a squirrel is 0.68 kg

It is placed at a height of 8 m above the ground.

It is required to find the gravitational potential energy of a squirrel. It is possessed by an object due to its position. Its formula is given by :

$E=mgh\\\\E=0.68\times 9.8\times 8\\\\E=53.312\ J$

So, the gravitational potential energy of a squirrel is 53.312 J.

7 0

3 years ago