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2 years ago

If it is safe to do so you should shut off your engine if it’s going to be idling for longer than?

Engineering

1 answer:

Lesechka [4]2 years ago

8 0

Answer: turn your ignition off it you are waiting more than 10 seconds

Explanation: idling for just 10 seconds waste more gas than restarting the engine and idling increases overall engine by causing the car to operate longer

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Consider steady heat transfer through the wall of a room in winter. The convection heat transfer coefficient at the outer surfac

AveGali [126]

The heat transfer which is in steady state, the heat transfer rate to the wall is equal to the wall.

<u>Explanation:</u>

The convection transfer of heat to the wall is

$Q=h A\left(T_{s}-T_{f}\right)$

Here, $T_{S}$ is the temperature of solid surface, $T_{f}$ is the temperature of moving fluid stream which is adjacent of solid surface, h is the heat transfer coefficient.
The coefficient of convection heat transfers outer surface contains 3 times to the inner surface which experience smaller drop of temperature for 3 times that compares to inner surface.
Hence, the temperatures outer surface get close to the surroundings of air temperature.

6 0

3 years ago

Which 2 items are most similar and why? Graduated Cylinder, Measuring Cup, Beaker

aivan3 [116]

Graduated cylinder & beaker; both are used for science activities while a measuring cup is mostly used for baking.

5 0

3 years ago

An electron is traveling with initial kinetic energy K in a uniform electric field. The electron comes to rest momentarily after

V125BC [204]

Answer:

a) E = $\frac{K}{e*d}$ b) i.

Explanation:

Assuming no other forces acting on the electron, as the field is pushing the electron back till it comes to rest momentarily, applying the work-energy theorem, the loss in kinetic energy, must be equal to the work done by the field on the electron.

The force that does work on the electron is the one due to the electric field E, and by definition of electric field, can be expressed as follows:

W = q*E = -e*E (1)

This work must be equal to the change in Kinetic Energy:

ΔK = Kf -K₀ = 0 - K = -K (2)

From (1) and (2), and solving for E, we have:

E = $\frac{K}{e*d}$

b) As the electric field (by convention) has the direction that it would have a positive test charge, the electrons (being negative charges),when starting from rest),have the direction opposite to the field.

In this case, as the electron has an initial velocity, and the field is opposing to the electron movement, we conclude that the electric field is in the direction of the electron´s motion, due to the electron slows down, and then comes momentarily to an stop, before changing direction and move opposite to the field as it is its natural behavior.

3 0

3 years ago

Consider the brass alloy for which the stress-strain behavior is shown in the Animated Figure 7.12. A cylindrical specimen of th

sleet_krkn [62]

Answer:

(a) 0.1509 mm

(b) 0.00525 mm

Explanation:

Stress, $\sigma$ is given by

$\sigma=\frac {F}{A}$ where F is force and A is area and area is given by $\frac {\pi d^{2}}{4}$ hence

$\sigma=\frac {4F}{\pi d^{2}}$ where d is the diameter. Substituting 9970 N for F and 10mm=0.01 m for d hence

$\sigma=\frac {4*9970 N}{\pi 0.01m^{2}}=126941982.6 N/m^{2}$

$\sigma \approx 127 Mpa$

From the attached stress-strain diagram, the stress of 127 Mpa corresponds to strain of 0.0015 and since strain is given by

$\epsilon=\frac {\triangle l}{l}$ where $\epsilon$ is the strain, $\triangle l$ is elongation and l is original length and making elongation the subject