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Trava [24]
1 year ago
6

A submarine completed a 450 km training with an average speed of 50 km/h. For the first 180 km, it travelled at an average speed

of 60 km/h. What was the average speed for the remaining distance? Km/h
Physics
1 answer:
Kryger [21]1 year ago
4 0

Answer:

45km/hr

Explanation:

Total distance=450km

Total speed=50km/hr

Total time= distance/speed

=450/50

=9hrs

distance a=180km

speed a=60km/hr

Time a=180/60

=3hrs

Distance b=450-180=270km

Speed b=?

Time b=270/speed b

Total time=time a + time b

9=3+(270/speed b)

270/speed b =9-3

270/speed b =6

6*speed b =270

Speed b=270/6

Speed b=45km/hr

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A stunt car driver testing the use of air bags drives a car at a constant speed of25 m/s for a total of 100m. He applies his bra
PIT_PIT [208]

Answer:

The graphs are attached

Explanation:

We are told that he starts with a constant speed of 25 m/s for a distance of 100 m.

At constant velocity, v = distance/time

time(t) = distance(d)/velocity(v)

t1 = 100/25

t1 = 4 s

Now, we are told that he applies his brakes and accelerates uniformly to a stop just as he reaches a wall 50m away.

It means, he decelerate and final velocity is zero.

Thus;

v² = u² + 2as

0² = 25² + 2a(50)

25² = - 100a

625 = - 100a

a = - 625/100

a = - 6.25 m/s²

v = u + at

0 = 25 + (-6.25t)

25 = 6.25t

t = 25/6.25

t = 4 s

With the values gotten, kindly find attached the distance-time and velocity-time graphs.

4 0
2 years ago
the water behind hoover dam in nevada is 206 m higher than the colorado river below it. at what rate must water pass through the
Nitella [24]

Answer:

the required mass flow rate is 49484.37 kg/s

Explanation:

Given the data in the question;

we first determine the relation for mass flow rate of water that passes through the turbine;

so the relation for net work on the turbine due to the change in potential energy considering 100% efficiency is;

W_{net} = m ( Δ P.E )

so we substitute (gh) for ( Δ P.E );

W_{net} = m (gh)

m = W_{net} / gh

so we substitute our given values into the equation

m = 100 MW / ( 9.81 m/s²) × 206 m

m = ( 100 MW × 10⁶W/MW) / ( 9.81 m/s²) × 206 m

m = 10 × 10⁷ / 2020.86

m = 49484.37 kg/s

Therefore, the required mass flow rate is 49484.37 kg/s

5 0
1 year ago
Three magnets are placed on a plastic stick as shown in the image. Explain how the magnets need to be rearranged so that they st
dimaraw [331]

Answer:

The magnets need to be placed with red closest to blue.

Opposite poles attract.

The magnets will be attracted to each other with enough force to stick together.

Explanation:

6 0
1 year ago
Read 2 more answers
Marcus can drive his boat 24 miles down the river in 2 hours but takes 3 hours to return upstream. Find the rate of the boat in
notsponge [240]

Answer:

speed of boat as

v_b = 10 mph

river speed is given as

v_r = 2 mph

Explanation:

When boat is moving down stream then in that case net resultant speed of the boat is given as

since the boat and river is in same direction so we will have

v_1 = v_r + v_b

Now when boat moves upstream then in that case the net speed of the boat is opposite to the speed of the river

so here we have

v_2 = v_b - v_r

as we know when boat is in downstream then in that case it covers 24 miles in 2 hours

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also when it moves in upstream then it covers same distance in 3 hours of time

v_2 = \frac{24}{3} = 8 mph

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so we have speed of boat as

v_b = 10 mph

river speed is given as

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8 0
1 year ago
Read 2 more answers
What is the least possible initial kinetic energy in the oxygen atom could have and still excite the cesium atom?
guapka [62]
K=E[(m+M)/M]

Kmin=4.4
8 0
1 year ago
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