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3 years ago

On a hypothetical scale X The ice point is 40° and steam point is 120°.

Physics

1 answer:

arlik [135]3 years ago

7 0

Answer:

The reading of Y is -10°.

Explanation:

For scale X, the ice point is 40° and steam point is 120°.

Difference between the two extremes for scales X = 120 - 40 = 80

For scale X, the ice point and steam points are -30° and 130° respectively.

Difference between the two extremes for scales X = 130 - (-30) = 160

Comparing both scales:

One unit of scale X = x

One unit of scale Y = y

Scale X has 80 divisions while scale Y has 160

80x = 160y

x = 2y

50° in scale X = 10x + ice point in X scale

10 divisions in Y scale = 20y

Reading of Y scale = ice point of Y + 20y

= -30° + 20°

= -10°

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A car is strapped to a rocket (combined mass = 661 kg), and its kinetic energy is 66,120 J.

Katen [24]

Answer:

9.4 m/s

Explanation:

The work-energy theorem states that the work done on an object is equal to the change in kinetic energy of the object.

So we can write:

$W=K_f - K_i$

where in this problem:

W = -36.733 J is the work performed on the car (negative because its direction is opposite to the motion of the car)

$K_i = 66,120 J$ is the initial kinetic energy of the car

$K_f$ is the final kinetic energy

Solving for Kf,

$K_f = W+K_i = -36,733+66,120=29,387 J$

The kinetic energy of the car can be also written as

$K_f = \frac{1}{2}mv^2$

where:

m = 661 kg is the mass of the car

v is its final speed

Solving, we find

$v=\sqrt{\frac{2K}{m}}=\sqrt{\frac{2(29,387)}{661}}=9.4 m/s$

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3 years ago

Calculate the average velocity of object over the first 10 seconds of the trip

kirza4 [7]

Answer:

in order to find the average velocity use change in Displacement / change in time?

Explanation:

6 0

3 years ago

An attacker at the base of a castle wall 3.65 m high throws a rock straight up with speed 7.4m/s from a height of 1.55m above th

Natali5045456 [20]

a) Yes, the rock will reach the top

b) The final speed is 3.7 m/s

c) The change in speed is 2.4 m/s

d) The change in speed in the two situations do not agree

e) Because the kinetic energy depends quadratically on the speed, $K\propto v^2$

Explanation:

The mechanical energy of the rock at the moment it is thrown from the ground is equal to the sum of its kinetic energy and its potential energy:

$E=KE_i + PE_i = \frac{1}{2}mu^2 + mgh_i$

where

m is the mass of the rock

u = 7.4 m/s is the inital speed

$g=9.8 m/s^2$ is the acceleration of gravity

$h_i = 1.55 m$ is the initial height of the rock

Substituting, we find the initial mechanical energy of the rock

$E=\frac{1}{2}m(7.4)^2 + m(9.8)(1.55)=42.6m$ [J]

In order to reach the top of the castle, the rock should have a mechanical energy of at least

$E' = mgh'$

where

h' = 3.65 m is the heigth of the top

Substituting,

$E'=m(9.8)(3.65)=35.6m$ [J]

Since E > E', it means that the rock has enough mechanical energy to reach the top.

The final mechanical energy of the rock at the top is

$E=mgh'+ \frac{1}{2}mv^2$ (1)

where:

v is the final speed of the rock at the top

Since the mechanical energy is conserved, this should be equal to the initial mechanical energy:

$E=42.6 m$ [J] (2)

Therefore, equating (1) and (2), we can find the final speed of the rock:

$mgh' + \frac{1}{2}mv^2 = 42.6m\\v=\sqrt{2(42.6-gh')}=\sqrt{2(42.6-(9.8)(3.65))}=3.7 m/s$

Since the motion of the rock is a free fall motion (constant acceleration equal to the acceleration of gravity), we can use the following suvat equation:

$v^2 - u^2 = 2as$

where

v is the final speed, at the bottom

u = 7.4 m/s is the initial speed of the rock, at the top

$a=9.8 m/s^2$ is the acceleration of gravity

s = 3.65 - 1.55 = 2.1 m is the vertical displacement of the rock

Solving for v, we find the final speed:

$v=\sqrt{u^2+2as}=\sqrt{7.4^2 + 2(9.8)(2.1)}=9.8 m/s$

Therefore, the change in speed is

$\Delta v = v-u = 9.8 - 7.4 =2.4 m/s$

In the first situation (rock thrown upward), we have:

u = 7.4 m/s (initial speed)

v = 3.7 m/s (final speed)

So the change in speed is

$\Delta v = v-u =3.7 - 7.4 = -3.7 m/s$

While the change in speed in the second situation (rock thrown downward) is

$\Delta v = 2.4 m/s$

Therefore, we see that their magnitudes do not agree.

In both situations, the change in kinetic energy of the rock is equal in magnitude to the change in gravitational potential energy, since the total mechanical energy is conserved.

The change in gravitational potential energy in the two situations is the same (because the change in height is the same), therefore the change in kinetic energy in the two situations is also the same.

However, the kinetic energy of the rock is not directly proportional to the speed, but to the square of the speed:

$K\propto v^2$

Since the initial speed is the same for both situation (7.4 m/s), but the change in kinetic energy has opposite sign in the two situations (negative when the rock is thrown upward, positive when thrown downward), the situation is not symmetrical, therefore in order to have the same magnitude of change in the kinetic energy, the change in speed must be larger when the kinetic energy involved is lower, so in the first situation.

Learn more about kinetic energy and about potential energy:

brainly.com/question/6536722

brainly.com/question/1198647

brainly.com/question/10770261

#LearnwithBrainly

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4 years ago

What relationship between the mass of each other and its motion after the collision do you observe? How do Newtons laws help exp

Leni [432]

Answer:

If the weight and forces are the same, it will result in a balance, i they are different, it will result in an overload in the lower force/mass object, reflecting it to the opposite direction with higher speed.

Explanation:

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3 years ago

How much current is in a circuit that includes a 9-volt battery with a resistance of 3

Darya [45]

Just remember
Voltage = current times resistance

current = voltage over resistance

Current = 9/3 = 3

7 0

3 years ago