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Keith_Richards [23]
2 years ago
13

A train travels 99 kilometers in 2 hours, and then 90 kilometers in 3 hours. What is its average speed?

Physics
1 answer:
Agata [3.3K]2 years ago
3 0

Average speed =

(total distance)/(total time)

Average speed = (99+90)/(2+3)

That's (189 km) / (5 hr)

Average speed = 37.8 km/hr

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An electric wall clock has a second hand 15 cm long. at the tip of his hand, what is the magnitude of the velocity?
Mila [183]

The velocity of the tip of the second hand is 0.0158 m/s

Explanation:

First of all, we need to calculate the angular velocity of the second hand.

We know that the second hand completes one full circle in

T = 60 seconds

Therefore, its angular velocity is:

\omega = \frac{2\pi}{T}=\frac{2\pi}{(60)}=0.105 rad/s

Now we can calculate the velocity of a point on the tip of the hand by using the formula

v=\omega r

where

\omega=0.105 rad/s is the angular velocity

r = 15 cm = 0.15 m is the radius of the circle (the distance of the point from the centre of rotation)

Substituting,

v=(0.105)(0.15)=0.0158 m/s

Learn more about angular motion here:

brainly.com/question/9575487

brainly.com/question/9329700

brainly.com/question/2506028

#LearnwithBrainly

7 0
2 years ago
This dude was sitting in the chair. Someone pulls the chair out from under him. He does not move in the direction of the chair.
Oksanka [162]

Answer:

This shows inertia because inertia is an object's resistance to change in motion. When the person (imma call them a she) who pulled the chair from under the guy did that, the chair was the one affected by the force of the girl, not the guy. The guy continued heading in the direction he was originally going, which was down.

At least, that's about how I would answer this question.

8 0
2 years ago
Which statement BEST describes Miguel Hidalgo?
tatiyna
Miguel Hidalgo was a Priest so I think it would be 1. 
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6 0
3 years ago
Read 2 more answers
A flywheel is a solid disk that rotates about an axis that is perpendicular to the disk at its center. Rotating flywheels provid
Sergeeva-Olga [200]

Answer:

8.37*10^5 rpm

Explanation:

Given that rotational kinetic energy = 4.66*10^9J

Mass of the fly wheel (m) = 19.7 kg

Radius of the fly wheel (r) = 0.351 m

Moment of inertia (I) = \frac{1}{2} mr ^2

Rotational K.E is illustrated as (K.E)_{rt} = \frac{1}{2} I \omega^2

\omega = \sqrt{\frac{2(K.E)_{rt}}{I} }

\omega = \sqrt{\frac{2(KE)_{rt}}{1/2 mr^2} }

\omega = \sqrt{\frac{4(K.E)_{rt}}{mr^2} }

\omega = \sqrt{\frac{4*4.66*10^9J}{19.7kg*(0.351)^2} }

\omega = 87636.04

\omega = 8.76*10^4 rad/s

Since 1 rpm = \frac{2 \pi}{60}  rad/s

\omega = 8.76*10^4(\frac{60}{2 \pi})

\omega = 836518.38

\omega = 8.37 *10^5 rpm

3 0
3 years ago
A typical jet airliner has a cruise airspeed of 900 km/h , which is its speed relative to the air through which it is flying. If
Luba_88 [7]

Explanation:

It is given that,

Speed of the jet airplane with respect to air, v_{PA} = 900\ km/h          

If the wind at the airliner’s cruise altitude is blowing at 100 km/h from west to east, v_{AG}= 100\ km/h

(A) Let v_{PG} is the speed of the airliner relative to the ground if the airplane is flying from west to east,

v_{PG}=900-100=800\ km/h

(B) Let v'_{PG} is the speed of the airliner relative to the ground if the airplane is flying from east to west,

v'_{PG}=900+100=1000\ km/h

Hence, this is the required solution.                                            

8 0
3 years ago
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