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Bumek [7]
4 years ago
15

The​ time, t, required to drive a fixed distance varies inversely as the​ speed, r. It takes 9 hr at a speed of 20 ​km/h to driv

e a fixed distance. How long will it take to drive the same distance at a speed of 23 ​km/h?
Physics
1 answer:
Harlamova29_29 [7]4 years ago
6 0

Answer:

Time=7.84hrs

Explanation:

This is an inverse proportionality questions

Mathematically time t varies as 1/distance d

Hence T= dk/r

But speed r = distance/t

d= r*t= 9*20=180km/hr

We're k= constant of proportionality

At t=9hrs d=180km/hr

Hence k=r*t/d=20*9/1620=0.111

Finding t at at 1620km for 23km/hr

t=1620*0.111/23=7.84hrs

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I think that the angular velocity vector points at right angles to the direction in which the wheels are turning (spindle on an old fashioned record player ?) and so at right angles to the direction the bike is moving in. This contributes to the gyroscope effect on the wheels and bike and allows a rapidly rotating wheel to be more stable than a slowly rotating one. Problem for the trainee cyclist is to believe that they are actually more stable when their wheels are moving quickly. 'cos the tendency is to go slowly to start with, which makes balancing harder. 
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4 0
4 years ago
A stone thrown off a bridge 10m above a river has an initial velocity of 8ms at an angle of 25 degrees above the horizontal. Wha
Darina [25.2K]

Explanation:

It is given that,

Height above which the stone was thrown, h = 10 m

Initial velocity of the stone, u = 8 m/s

Angle above the horizontal, \theta=25^{\circ}

The horizontal component of velocity is, u_x=v\ cos\theta=8\ cos(25)=7.25\ m/s

The vertical component of velocity is, u_y=v\ sin\theta=8\ cos(25)=3.38\ m/s

Let t is the time of flight in vertical motion. The second equation of motion is :

h=u_yt-\dfrac{1}{2}gt^2

10=3.38t-\dfrac{1}{2}\times 9.8t^2      

t = 0.34 seconds

Let s is the range of the stone. It can be calculated as :

s=u_x\ cos\theta \times t

s=7.25\times 0.34

s = 2.46 meters

So, the range of the stone is 2.46 meters. Hence, this is the required solution.

7 0
3 years ago
How much energy is required to raise the temperature of 5g of air by 10°C?
Alex777 [14]
You need to know the specific heat capacity of air.
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4 0
3 years ago
A particular cylindrical bucket has a height of 36.0 cm, and the radius of its circular cross-section is 15 cm. The bucket is em
Andrew [12]

Answer:

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Explanation:

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P_2 = Final pressure = P_a+\rho_w gh

h = Depth of cylinder = 36 cm

g = Acceleration due to gravity = 10 m/s²

\rho_w = Density of water = 1000 kg/m³

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4 years ago
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Answer:

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