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Artemon [7]
3 years ago
7

An train car of total mass of 13000 kg is pulling into a station and slowing down with an acceleration of -4.56 m/s^2. Before th

e train pulls into the station, a group of 7 stowaway jump off the train. Each stowaway has a mass of 66 kg. If the braking force on the train remains the same, what will be the acceleration of the train once the stowaways jump out of the train?

Physics
1 answer:
lys-0071 [83]3 years ago
4 0
<h3>Answer:</h3>

-4.73 m/s²

<h3>Explanation:</h3>

Each jumper represents about 1/2 of 1% of the mass of the train, so together they total about 3.5% of the mass of the train. If the mass decreases by 3.5% and the braking force remains the same, the acceleration (magnitude) will increase by about 3.5%.

The acceleration will be about 0.17 m/s² more (in magnitude) than it was, or about -4.73 m/s².

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A river 800m wide flows at the rate of 5km/h . A swimmer who can swim at 10km/h in still water wants to cross the river straight
LuckyWell [14K]

Answer:

At an angle of 30^{\circ}

Explanation:

Assume the river flows from East to West so for the swimmer to cross across it, assume he crosses it from West to East.

The resultant speed will be given by

R= \sqrt {10^{2}-5^{2}=\sqrt {75}\approx 8.66 km/h\\Direction=sin^{-1}\frac {5}{10}\approx 30^{\circ}

6 0
2 years ago
Two identical loudspeakers 2.00 m apart are emitting sound waves into a room where the speed of sound is 340 m/s. Abby is standi
ki77a [65]

Answer:

The lowest possible frequency of sound for which this is possible is 1307.69 Hz

Explanation:

From the question, Abby is standing 5.00m in front of one of the speakers, perpendicular to the line joining the speakers.

First, we will determine his distance from the second speaker using the Pythagorean theorem

l₂ = √(2.00²+5.00²)

l₂ = √4+25

l₂ = √29

l₂ = 5.39 m

Hence, the path difference is

ΔL = l₂ - l₁

ΔL = 5.39 m - 5.00 m

ΔL = 0.39 m

From the formula for destructive interference

ΔL = (n+1/2)λ

where n is any integer and λ is the wavelength

n = 1 in this case, the lowest possible frequency corresponds to the largest wavelength, which corresponds to the smallest value of n.

Then,

0.39 = (1+ 1/2)λ

0.39 = (3/2)λ

0.39 = 1.5λ

∴ λ = 0.39/1.5

λ = 0.26 m

From

v = fλ

f = v/λ

f = 340 / 0.26

f = 1307.69 Hz

Hence, the lowest possible frequency of sound for which this is possible is 1307.69 Hz.

5 0
3 years ago
How much power does it take to lift a 30.0 n box 10.0 m high in 5.00 s, if you must apply a 62n force to lift the box?
Illusion [34]
Power is defined as the rate at which the body is doing work:
P=\frac{W}{t}
Work is defined as displacement done by the force times that displacement:
W=F\cdot h
We know that we need 62N to move the box, so when we apply this force along the path of 10m we have done:
W=62N\cdot10m=620J
of work.
Now we just divide that by 5s to get how much power is required:
P=\frac{620J}{5s}=124W
5 0
2 years ago
A 100-N force causes an object to<br> accelerate at 2 m/s/s. What is the<br> mass of the object?
Kitty [74]

Answer:

50\; \rm kg.

Explanation:

By Newton's Second Law, the acceleration a of an object is proportional to the net force \sum F on it. In particular, if the mass of the object is m, then

\sum F = m \cdot a.

Rewrite this equation to obtain:

\displaystyle m = \frac{\sum F}{a}.

In this case, the assumption is that the 100\; \rm N force is the only force that is acting on the object. Hence, the net force \sum F on the object would also be

Make sure that all values are in their standard units. Forces should be in Newtons (same as \rm kg \cdot m \cdot s^{-2}, and the acceleration of the object should be in meters-per-second-squared (\rm m \cdot s^{-2}). Apply the equation \displaystyle m = \frac{\sum F}{a} to find the mass of the object.

\displaystyle m = \frac{100\; \rm N}{2\; \rm m \cdot s^{-2}} = 50\; \rm kg.

4 0
2 years ago
Why is specific heat important
Ad libitum [116K]
Hey!!

here is your answer >>>

Specific heat is the amount of heat required to raise the temperature of a unit substance!. The most common example!. The specific heat of water is 1 !. And, lot of plays and animals live under the water and if the specific heat of the water would be low, then the aquatic organisms would die, but the specific heat is high and it is hard for the sun to increase the temperature!.

Hope my answer helps!
3 0
2 years ago
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