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agasfer [191]
3 years ago
5

Liz rushes down onto a subway platform to find her train already departing. she stops and watches the cars go by. each car is 8.

60 m long. the first moves past her in 1.80 s and the second in 1.66 s. find the constant acceleration of the train.
Physics
1 answer:
Snezhnost [94]3 years ago
5 0

 

The average velocity can be calculated using the formula:

v = d / t

For the 1st car, the velocity is calculated as:

v1 = 8.60 m / 1.80 s = 4.78 m / s

While that of the 2nd car is:

v2 = 8.60 m / 1.66 s = 5.18 m / s

 

Now we can solve for the acceleration using the formula:

v2^2 = v1^2 + 2 a d

Rewriting in terms of a:

a = (v2^2 – v1^2) / 2 d

a = (5.18^2 – 4.78^2) / (2 * 8.6)

a = 0.23 m/s

 

Therefore the train has a constant acceleration of about 0.23 meters per second.

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On Earth, a spring stretches by 5.0 cm when a mass of 3.0 kg is suspended from one end.
Neko [114]

Answer:

Mass = 18.0 kg

Explanation:

From Hooke's law,

F = ke

where: F is the force, k is the spring constant and e is the extension.

But, F = mg

So that,

mg = ke

On the Earth, let the gravitational force be 10 m/s^{2}.

3.0 x 10 = k x 5.0

30 = 5k

⇒ k = \frac{30}{5} ................ 1

On the Moon, the gravitational force is \frac{1}{6} of that on the Earth.

m x \frac{10}{6} = k x 5.0

\frac{10m}{6} = 5k

⇒ k = \frac{10m}{30} ............. 2

Equating 1 and 2, we have;

\frac{30}{5}  = \frac{10m}{30}

m = \frac{900}{50}

    = 18.0

m = 18.0 kg

The mass required to produce the same extension on the Moon is 18 kg.

8 0
3 years ago
Read 2 more answers
A student is told to use 20.0 g of sodium chloride to make an aqueous solution that has a concentration of 10.0 g/L (grams of so
Stells [14]

Answer:

she should add solute to the solvent

Explanation:

Given data :

Mass of the sodium chloride, = 20.0 g

Concentration of the solution = 10 g/L

Volume of 20.0 g of sodium chloride = 7.50 mL

Now, from the concentration, we can conclude that for 10 g of sodium chloride volume of the solution is 1 L

thus, for 20 g of sodium chloride  volume of the solution is 2 L or 2000 mL

also,

Volume of solution = Volume of solute(sodium chloride) + volume of solvent (water)

thus,

2000 mL = 7.5 mL + volume of solvent (water)

or

volume of water = (2000 - 7.5) mL

or

volume of water = 1992.5 mL

or

volume of water = 199.25 L ≈ 199 L

6 0
3 years ago
Read 2 more answers
The average speed during any time interval is equal to the total distance of travel divided by the total time. Let d represent t
Tanya [424]

Answer:

Average speed = 3.63 m/s

Explanation:

The average speed during any time interval is equal to the total distance travelled divided by the total time.

That is,

Average speed = distance/ time

Let d represent the distance between A and B.

Let t1 be the time for which she has the higher speed of 5.15 m/s. Therefore,

5.15 = d/t1.

Make d the subject of formula

d = 5.15t1

Let t2 represent the longer time for the return trip at 2.80 m/s . That is,

2.80 = d/t2.

Then the times are t1 = d/5.15 5 and

t2 = d/2.80.

The average speed vavg is given by the following equation.

avg speed = Total distance/Total time

Avg speed = d + d/t1 + t2

Where

Total distance = 2d

Total time = t1 + t2

Total time = d/5.15 + d/2.80

Total time = (2.8d + 5.15d)/14.42

Total time = 7.95d/14.42

Total time = 0.55d

Substitute total distance and time into the formula above.

Avg speed = 2d / 0.55d

Avg Speed = 3.63 m/s

7 0
3 years ago
If you were stuck in the center of the bridge when it was swaying, where would be the safest place to walk back to land?
Ludmilka [50]
Straight
You already have to momentum of walking forward, and going back and forth are the same distance. If you go back then you would have to stop, turn and walk, but if you go forward you just have to walk.
4 0
3 years ago
A soccer player runs with a speed of 4.6m/s how long does it take him to run 60m
Misha Larkins [42]

To solve this problem divide 60 by 4.6

The answer to this problem is 13 seconds.

3 0
3 years ago
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