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Marrrta [24]
3 years ago
6

In countries where there is very hot and very cold weather, should the gaps between the lengths of railway track be wider or nar

rower?
Physics
1 answer:
kipiarov [429]3 years ago
5 0
They should be bigger as if it is hot the tracks will expand as it is made of metal and then there is more room for it to expand or contract
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A 5.0-kg object is pulled along a horizontal surface at a constant speed by a 15-n force acting 20° above the horizontal. How mu
puteri [66]

Answer:

84.6 J

Explanation:

The work done by the force is given by

W=Fd cos \theta

where

W is the work done

F = 15 N is the force applied

d = 6.0 m is the displacement

\theta=20^{\circ} is the angle between the force's direction and the displacement

Substituting the numbers into the equation, we find

W=(15 N)(6.0 m)cos 20^{\circ} =84.6 J

3 0
3 years ago
A 425 g block is released from rest at height h0 above a vertical spring with spring constant k = 460 N/m and negligible mass. T
Morgarella [4.7K]

Answer:

(a) = +5.38m (b) = -5.38m (c) = 1.246m (d) = +0.3771m.

Explanation:

Initially the spring is at equilibrium,

Work done by all forces = change in kinetic energy

Work = ∇K.E

Work = Kf -Ki =0

Since the work done = 0 since the body is at rest.

W(spring) + W(gravity) = 0

W(spring) + W(gravity) = 0

W(spring) = -W(gravity)

Work done by the block on the spring = W(block/spring)

W(block/spring) + W(spring) = 0

W(spring) = -∫kx.dx

W(spring) = ½k(X²i - X²f) ; Xi =0, Xf = 15.3cm = 0.153m

W(spring) = -½* 460 * (0.153)²

W(spring) = - 5.38NM

Work done by block on spring = + 5.38NM

(b). Workdone by spring on the block = -5.38NM.

Note: This is so because the displacement of the force is in the opposite direction to the previous one since they counter each other to maintain equilibrium.

(C). W(spring) +W(gravity) = 0

½kx² + mg(h + x) = 0

-5.83 + mg(h + 0.153) =0

5.83 = 0.425*9.8 (h + 0.153)

5.83 = 4.165(h + 0.153)

H = 1.399 - 0.153

H = 1.246m

(D).

If the release height was 6ho

H = 6* 1.246m = 7.476m

W(spring) = W(gravity)

½kx² = mg(7.476 + x)

Note: At maximum compression, the blocks would be at rest.

½Kx² = mg(h + x)

½ * 460 * x² = 0.425 * 9.8 * (7.476 + x)

230x² = 4.165 (7.476 + x)

230x² = 31.137 + 4.165x

230x² - 4.165x - 31.137 = 0

Solving the quadratic equation ( i would suggest you use formula method for easy navigation of the variables)

X = + 0.3771m or -0.3589m

But we can't have a negative compression value,

X = + 0.3771m

7 0
3 years ago
Read 2 more answers
Which of the following is a good conductor of heat? 1. water 2. glass 3. wood 4. mercury​
trapecia [35]

Answer:

So the answer would be water based on the evidence shown below.

Explanation:

Mercury is a poor conductor of heat but good for electricity, water is a good conductor of heat but a poor conductor of electricity, wood is a poor conductor of heat and electricity, and glass is probably the worst conductor of heat.

7 0
3 years ago
The Sun has a mass of 1.99x10^30 kg and a radius of 6.96x10^8 m. Calculate the acceleration due to gravity, in meters per second
just olya [345]

Answer:

g=274\ m/s^2

Explanation:

Mass of the Sun, M=1.99\times 10^{30}\ kg

The radius of the Sun, r=6.96\times 10^8\ m

We need to find the acceleration due to gravity on the surface of the Sun. It is given by the formula as follows :

g=\dfrac{GM}{r^2}\\\\g=\dfrac{6.67\times 10^{-11}\times 1.99\times 10^{30}}{(6.96\times 10^8)^2}\\\\g=274\ m/s^2

So, the value of acceleration due to gravity on the Sun is 274\ m/s^2.

8 0
3 years ago
Thiết bị nào sau đây không phải là nguồn điện
kumpel [21]

Thiết bị không phải nguồn điện:

Đáp án D

7 0
3 years ago
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