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Viefleur [7K]
3 years ago
9

Which of the following statements are true?

Physics
1 answer:
inessss [21]3 years ago
7 0

Answer:

a. If an object's speed is constant, then its acceleration must be zero.

FALSE

As we know that acceleration is defined as the rate of change in velocity

a = \frac{d\vec v}{dt}

so we can not say anything about the acceleration when speed is given to as and no information is given about velocity

b. If an object's acceleration is zero, then its speed must be constant.

TRUE

As we know that acceleration is defined as the rate of change in velocity

a = \frac{d\vec v}{dt}

Since we know that if acceleration is 0 then velocity must be constant and hence speed is also constant

c. If an object's velocity is constant, then its speed must be constant.

TRUE

Since velocity is constant then it shows that its magnitude and direction both are constant so its speed is also constant.

d. If an object's acceleration is zero, its velocity must be constant.

TRUE

As we know that acceleration is defined as the rate of change in velocity

a = \frac{d\vec v}{dt}

Since we know that if acceleration is 0 then velocity must be constant

e. If an object's speed is constant, then its velocity must be constant.

FALSE

Speed is just the magnitude so we can not say about its direction and hence if speed is constant then velocity may or may not change

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Given that an electric field of 3×106V/m3×106V/m is required to produce an electrical spark within a volume of air, estimate the
Andre45 [30]

Answer:

Length, l = 33.4 m

Explanation:

Given that,

Electrical field, E=3\times 10^6\ V/m

Let the electrical potential is, V=10^8\ V

We need to find the length of a thundercloud lightning bolt. The relation between electric field and the electric potential is given by :

V=E\times d\\\\d=\dfrac{V}{E}\\\\d=\dfrac{10^8}{3\times 10^6}\\\\d=33.4\ m

So, the length of a thundercloud lightning bolt is 33.4 meters. Hence, this is the required solution.

5 0
3 years ago
The power is inversely proportional with time
trapecia [35]

Answer:

True

Explanation:

Given that Power whose unit is Watt equates to one joule of work per second. It implies that Power is directly proportional to the work done and inversely proportional to the time to do the work.

Therefore, in this case, the right answer to the question is that it is TRUE that the power is inversely proportional with time

8 0
3 years ago
9. What force is felt on a person when they 'free-fall down a large roller<br> coaster hill?
spin [16.1K]
Gravity is counteracted by centripetal force, due to acceleration, which is the force that pushes you into your seat.
7 0
3 years ago
In which case would electrical potential energy be built up and stored in the electric field? a) A positive charge is moved towa
mr_godi [17]

Answer:

The correct option is B

Explanation:

Although, it is common knowledge that in an electric field, unlike charges attract and like charges repel. However, to build up an electric potential, a positive charge is brought close to another positive charge - this causes work done to be changed to electric potential energy and stored in the electric field.

It should however be noted that when a negative charge is moved away from a positive charge, the negative charge gains electric potential energy.

5 0
2 years ago
You have a source of energy containing 21 gj of energy at 600k how much this energy can be converted to work when rejecting heat
sweet [91]

Answer:

Available energy = 35 x 10⁶ J

Explanation:

Given:

Amount of energy (Q) = 21 gj = 21 x 10⁹ J

Temperature T1 = 600 k

Temperature T0 = 27 + 273 = 300k

Find:

Available energy

Computation:

Available energy = Q[1/T0 - 1/T1]

Available energy = 21 x 10⁹ J[1/300 - 1/600]

Available energy = 35 x 10⁶ J

4 0
2 years ago
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