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vredina [299]
3 years ago
13

Suppose a car travels 106 km at a speed of 28 m/s and uses 1.9 gals of gasoline in the process. Only 30% of the gasoline goes in

to useful work to keep the car moving at a constant speed.
In this problem, you may assume that 1 gallon of gasoline produces 1.2 × 10^8 J of energy.
(a) What is the magnitude of the force exerted to keep the car moving at constant speed?
(b) If the required force is directly proportional to speed, how many gallons will be used to drive 106 km at a speed of 28.0 m/s?
Physics
1 answer:
USPshnik [31]3 years ago
6 0

Answer:

a) The magnitude of the force is 968 N

b) For a constant speed of 30 m/s, the magnitude of the force is 1,037 N

Explanation:

<em>NOTE: The question b) will be changed in other to give a meaningful answer, because it is the same speed as the original (the gallons would be 1.9, as in the original).</em>

Information given:

d = 106 km = 106,000 m

v1 = 28 m/s

G = 1.9 gal

η = 0.3

Eff = 1.2 x 10^8 J/gal

a) We can express the energy used as the work done. This work has the following expression:

W=F\cdot d

Then, we can derive the magnitude of the force as:

F=\frac{W}{d}=\frac{\eta\cdot (G\cdot Eff)}{d}=\frac{0.3*1.9*(1.8*10^8)}{106*10^3} =968\,N

b) We will calculate the force for a speed of 30 m/s.

If the force is proportional to the speed, we have:

F_2=F_1(\frac{v_2}{v_1} )=968(\frac{30}{28} )=968*1.0714=1,037\,N

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The spin cycle of a clothes washer extracts the water in clothing by greatly increasing the water's apparent weight so that it i
andreyandreev [35.5K]

The apparent weight of a 1.1 g drop of water is 4.24084 N.

<h3>What is Apparent Weight?</h3>
  • According to physics, an object's perceived weight is a characteristic that describes how heavy it is. When the force of gravity acting on an object is not counterbalanced by a force of equal but opposite normality, the apparent weight of the object will differ from the actual weight of the thing.
  • By definition, an object's weight is equal to the strength of the gravitational force pulling on it. It follows that even a "weightless" astronaut in low Earth orbit, with an apparent weight of zero, has almost the same weight that he would have if he were standing on the ground; this is because the gravitational pull of low Earth orbit and the ground are nearly equal.

Solution:

N = Speed of rotation = 1250 rpm

D = Diameter = 45 cm

r = Radius = 22.5 cm

M = Mass of drop = 1.1 g

Angular speed of the water = \omega  = \frac{2\pi N}{60}

\omega  = \frac{2\pi \times 1250}{60}

\omega  = 130.89 rad/s

Apparent weight is given by

W _a = M\omega^{2}R

W_a = 1.1 \times 10^-^3\times (130.89)^2\times 0.225

W_a = 4.24084 N

Know more about Apparent weight brainly.com/question/14323035

#SPJ4

Question:

The spin cycle of a clothes washer extracts the water in clothing by greatly increasing the water's apparent weight so that it is efficiently squeezed through the clothes and out the holes in the drum. In a top loader's spin cycle, the 45-cm-diameter drum spins at 1250 rpm around a vertical axis. What is the apparent weight of a 1.1 g drop of water?

7 0
2 years ago
A cyclist is traveling 10 m/s with an acceleration of 6 m/s2. How fast is the cyclist traveling at the end of 20 seconds
krok68 [10]

Answer:

<em>The cyclist is traveling at 130 m/s</em>

Explanation:

<u>Constant Acceleration Motion </u>

It's a type of motion in which the velocity of an object changes by an equal amount in every equal period of time.

Being a the constant acceleration, vo the initial speed, vf the final speed, and t the time, the following relation applies:

v_f=v_o+at

The cyclist initially travels at 10 /s and it's accelerating at a=6m/s^2. We need to know the new speed when t= 20 seconds have passed.

Apply the above equation:

v_f=10+6\cdot 20

v_f=10+120

v_f=130\ m/s

The cyclist is traveling at 130 m/s

7 0
3 years ago
To charge an electroscope negatively by induction you need: a) a positively charged rod and a ground b) a negatively charged rod
Zolol [24]

Answer:

Option a)

Explanation:

In the process of charging anything by the method of induction, a charged body is brought near to the body which is neutral or uncharged without any physical contact and the ground must be provided to the uncharged body.

The charge is induced and the nature of the induced charge is opposite to that of the charge present on the charged body.

So when a positively charged rod is used to charge an electroscope, the rod which is positive attracts the negative charge in the electroscope and the grounding of the electroscope ensures the removal of the positive charge and renders the electroscope negatively charged.

6 0
3 years ago
Calculate the frequency of the red light emitted by a neon sign with a wavelength of 690 nm
Ne4ueva [31]

Answer:

4.35 \times 10^{14} Hz

Explanation:

The frequency of a light is inversely proportional to its wavelength. It is given by:

f = \frac{v}{\lambda}

The speed of the red light, v = 3.0 × 10⁸ m/s

The wavelength of the red light, λ = 690 nm = 690 ×10⁻⁹ m

f = \frac{3.0 \times 10^8 m/s}{690\times 10^{-9}m} = 4.35 \times 10^{14} Hz

Thus, the frequency of red light emitted by neon sign having wavelength 690 nm is 4.35 \times 10^{14} Hz

7 0
3 years ago
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You visit the Grand Canyon on a particularly hot day, and like all good tourists, you yell "Hello!". Would you expect to hear th
RUDIKE [14]

Answer:

Hear echo sooner on a hot day than on a cooler day.

Explanation:

Temperature is one of the factors that determine the speed of sound. Speed of sound, which in this case is echo is calculated considering distance and time. Speed of sound is directly proportional to the temperature , therefore, when the temperature is hot, the speed of sound is faster than when the temperature is cold and vice versa. In conclusion, you would expect to hear the echo “hello” sooner on a hot day compared to a cold day provided all the other factors are kept constant.

7 0
3 years ago
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