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4 years ago

When an object stops moving, changes speed, or changes direction, how does a scientists describe that condition?

Physics

1 answer:

soldi70 [24.7K]4 years ago

5 0

The answer is A. unbalanced forces

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M 25 m in the distance traveled and an uncertainty of 1 s in the elapsed time. (a) calculate the percent uncertainty in the dist

Viefleur [7K]

The answer for sub question A) calculate the percent uncertainty in the distance is 0.059%.

The answer for sub question B) calculate the uncertainty in the elapsed time is 9,012 s

The answer for sub question C) what is the average speed in meters per second is 4.681 m/s

The answer for sub question D) what is the uncertainty in the average speed is 0.0032 m/s

<h3>How are the answers calculated?</h3>

To calculate the percentage of uncertainty of distance we have uncertainty = 25 m and distance = 42.188 km which is 42188 m.

Now $\frac{25}{42188}$ x 100% = 0.059%

To calculate time elapsed, we have the following data:

2hr which is 7200 s, 30 min which is 1800 s and 12 s

Adding these all up, we get 9012 s.

The average speed in m/s is calculated by 42188 m/ 9012 s = 4.681 m/s

The uncertainty in average speed is calculated by 4.681 m/s x $\frac{0.059 + 0.01}{100}$

= 0.0032 m/s

To know more about uncertainty in physics, visit:

brainly.com/question/28216820

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The complete question is A marathon runner completes a 42.188 km course in 2 h , 30 min, and 12 s . There is an uncertainty of 25 m in the distance traveled and an uncertainty of 1 s in the elapsed time. (a) Calculate the percent uncertainty in the distance. (b) Calculate the uncertainty in the elapsed time. (c) What is the average speed in meters per second? (d) What is the uncertainty in the average speed?

3 0

2 years ago

A hydraulic turbine is used to generate power by using the water in a dam. The elevation difference between the free surfaces up

Serjik [45]

Answer:

0.906

Explanation:

Let g = 9.81 m/s2. We can calculate the rate of change in potential energy when m = 201kg of water is falling down a distance of h = 131m per second

$\dot{E_p} = \dot{m}gh = 201*9.81*131 = 258307 J/s (W) = 258.307 kW$

So the efficiency of the water turbine is the ratio of output power over input power:

$\frac{234}{258.307} = 0.906$

3 0

4 years ago

What mass of steam at 100°C must be mixed with 490 g of ice at its melting point, in a thermally insulated container, to produce

sukhopar [10]

Answer:

the mass of steam at 100°C must be mixed is 150 g

Explanation:

given information:

ice's mass, $m_{i}$ = 490 g = 0.49 kg

steam temperature, T = 100°C

liquid water temperature, T = 89.0°C

specific heat of water, $c_{w}$ = 4186 J/kg.K = 4.186 kJ/kg.K

latent heat of fusion, $L_{f}$ = 333 kJ/kg

latent heat of vaporization, $L_{v}$ = 2256 kJ/kg

first, we calculate the heat of melted ice to water

Q₁ = $m_{i} L_{f}$

where

Q = heat

$m_{i}$ = mass of the ice

$L_{f}$ = latent heat of fusion

thus,

Q₁ = $m_{i} L_{f}$

= 0.49 x 333

= 163.17 kJ

then, the heat needed to increase the temperature of water to 89.0°C

Q₂ = $m_{i}$ $c_{w}$ (89 - 0), the temperature of ice is 0°C

$c_{w}$ = specific heat of water

so,

Q₂ = $m_{i}$ $c_{w}$ (89 - 0)

= 0.49 x 4.186 x 89

= 182.55 kJ

so, the heat absorbed by the ice is

Q = Q₁ + Q₂

= 163.17 + 182.55

= 345.72 kJ

the temperature of the steam is 100°C, so the mass of the steam is

Q = $m_{s}$ $L_{v}$ + $m_{s}$ $c_{w}$ (100 - 89)

Q = $m_{s}$ ( $L_{v}$ + $c_{w}$ (11))

$m_{s}$ = Q/ [ $L_{v}$ + $c_{w}$ (11)]

= 345.72/ [2256 + (4.186 x 11)]

= 0.15 kg

= 150 g

5 0

3 years ago

two astronauts are taking a spacewalk outside the International Space Station the first astronaut has a mass of 64 kg the second

Fittoniya [83]

Answer:

Approximately $0.88\; {\rm m \cdot s^{-1}}$ to the right (assuming that both astronauts were originally stationary.)

Explanation:

If an object of mass $m$ is moving at a velocity of $v$ , the momentum $p$ of that object would be $p = m\, v$ .

Since momentum of this system (of the astronauts) conserved:

$\begin{aligned} &(\text{Total Final Momentum}) \\ &= (\text{Total Initial Momentum})\end{aligned}$ .

Assuming that both astronauts were originally stationary. The total initial momentum of the two astronauts would be $0$ since the velocity of both astronauts was $0\!$ .

Therefore:

$\begin{aligned} &(\text{Total Final Momentum}) \\ &= (\text{Total Initial Momentum})\\ &= 0\end{aligned}$ .

The final momentum of the first astronaut ( $m = 64\; {\rm kg}$ , $v = 0.8\; {\rm m\cdot s^{-1}}$ to the left) would be $p_{1} = m\, v = 64\; {\rm kg} \times 0.8\; {\rm m\cdot s^{-1}} = 51.2\; {\rm kg \cdot m \cdot s^{-1}}$ to the left.

Let $p_{2}$ denote the momentum of the astronaut in question. The total final momentum of the two astronauts, combined, would be $(p_{1} + p_{2})$ .

$\begin{aligned} & p_{1} + p_{2} \\ &= (\text{Total Final Momentum}) \\ &= (\text{Total Initial Momentum})\\ &= 0\end{aligned}$ .

Hence, $p_{2} = (-p_{1})$ . In other words, the final momentum of the astronaut in question is the opposite of that of the first astronaut. Since momentum is a vector quantity, the momentum of the two astronauts magnitude ( $51.2\; {\rm kg \cdot m \cdot s^{-1}}$ ) but opposite in direction (to the right versus to the left.)

Rearrange the equation $p = m\, v$ to obtain an expression for velocity in terms of momentum and mass: $v = (p / m)$ .

$\begin{aligned}v &= \frac{p}{m} \\ &= \frac{51.2\; {\rm kg \cdot m \cdot s^{-1}}}{64\; {\rm kg}} && \genfrac{}{}{0}{}{(\text{to the right})}{} \\ &\approx 0.88\; {\rm m\cdot s^{-1}} && (\text{to the right})\end{aligned}$ .

Hence, the velocity of the astronaut in question ( $m = 58.2\; {\rm kg}$ ) would be $0.88\; {\rm m \cdot s^{-1}}$ to the right.

5 0

2 years ago

If a star is hotter is the wavelength shorter and higher energy?

insens350 [35]

Answer:

That is true, the hotter a star is the shorter of wavelength it emits and the higher. It also depends on the mass of the star because the bigger it is, the faster it fuses its hydrogen fuel. Faster burning of fuel means more energy is released and so results in higher temperatures.

Hope this helps! Good luck :)

Explanation:

3 0

3 years ago

Read 2 more answers