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3 years ago

Which of the following statements about energy is true?

Physics

1 answer:

irina1246 [14]3 years ago

3 0

Answer:ll. Kinetic energy can be transformed into Potential energy.

And, lll. Potential energy can be transformed into Kinetic energy

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A car is traveling at a speed of 38.0 m/s on an interstate highway where the speed limit is 75.0 mi/h. Is the driver exceeding t

Tom [10]

Answer: Yes, he is exceeding the speed limit

Explanation:

Hi!

This is problem about unit conversion

1 mile = 1,609.344 m

Then the speed limit v is:

v = 75 mi/h = 120,700.8 m/h

1 hour = 60 min = 60*60 s = 3,600 s

v = (120,700.8/3,600) m/s = 33.52 m/s

38 m/s is higher than the speed limit v.

5 0

3 years ago

A 10-cm-long wire is pulled along a u-shaped conducting rail in a perpendicular magnetic field. the total resistance of the wire

Debora [2.8K]

In the above case we can say that power given by external agent to pull the rod must be equal to the power dissipated in the form of heat due to magnetic induction.

Part a)

when we pull the rod with constant speed then power required will be product of force and velocity

here we will have

$P = F.v$

P = 4 W

v = 4 m/s

now we will have

$4 = F*4$

$F = 1N$

So external force required will be 1 N

PART B)

now in order to find magnetic field strength we can say

$P = \frac{v^2B^2L^2}{R}$

here we know that induced EMF in the wire is E = vBL

so power due to induced magnetic field is given by

$P = \frac{E^2}{R}$

$4 = \frac{4^2*B^2*0.10^2}{0.20}$

by solving above equation we will have

$B = 2.24 T$

5 0

3 years ago

A block is released from rest, at a height h, and allowed to slide down an inclined plane. There is friction on the plane. At th

GREYUIT [131]

Here the block has two work done on it

1. Work done by gravity

2. Work done by friction force

So here it start from height "h" and then again raise to height hA after compressing the spring

So work done by the gravity is given as

$W_g = m_A g(h - h_A)$

Now work done by the friction force is to be calculated by finding total path length because friction force is a non conservative force and its work depends on total path

$W_f = -(\mu m_A g cos\theta)(\frac{h}{sin\theta} + \frac{h_A}{sin\theta})$

$W_f = -\mu m_A g cot\theta(h + h_A)$

Total work done on it

$W = m_A g(h - h_A) - \mu m_A g cot\theta(h + h_A)$

So answer will be

None of these

7 0

3 years ago

Read 2 more answers

Object A and Object B have the same volume of 10 cm³. Object A has a mass of 20 grams. Object B has a mass of 50 grams. Which ob

aniked [119]

Answer:

Object B has greater density

desity A=20/10=2 g cm^-3 . density B=50/10=5 g cm^-3

the object that has greater mass has the greater density because the volume of the those two objects are same

3 0

3 years ago

Which of the following statements is true? During heat flow, energy is converted to matter.

TEA [102]

Answer:

During heat flow, much of the energy is dissipated and cannot be used for useful work.

Explanation:

Which of the following statements is true?

During heat flow, much of the energy is lost.

During heat flow, energy is converted to matter.

During heat flow, much of the energy is dissipated and cannot be used for useful work.

3 0

3 years ago