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3 years ago

A joger travels 8.0 kilometers in 1.25 hours what is the average speed?

Physics

2 answers:

gogolik [260]3 years ago

8 0

8/1.25 = 6.4 kmph
The answer is 6.4 kilometers per hour

Svetach [21]3 years ago

3 0

ΔS = 8.0 km

ΔT = 1.25 h

Vm = ΔS / ΔT

Vm = 8.0 / 1.25

Vm = 6.4 Km/h

hope this helps!

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A police car is at rest parallel to the highway and measures the speed of cars. It sends the signal with a frequency of 1200 Hz,

masha68 [24]

Answer:

a) The car was moving at a speed of $29.167\ m.s^{-1}$

b) The negative sign of $v_o$ denotes that the observer is coming towards the police car which is the source of the sound.

c) $f_o=1283.33\ Hz$

Explanation:

Given:

original frequency of the source, $f=1200\ Hz$

speed of the source, $v_s=0\ m.s^{-1}$

velocity of the obstacle car be, $v_o$

speed of sound, $s=350\ m.s^{-1}$

observed frequency, $f_o=1100\ Hz$

<u>Using the equation from the Doppler's effect:</u>

$\frac{f_o}{f} =\frac{(s+v_o)}{(s-v_s)}$

$\frac{1100}{1200} =\frac{(350+v_o)}{350-0}$

$v_o=-29.167\ m.s^{-1}$

The car was moving at a speed of $29.167\ m.s^{-1}$

The negative sign of $v_o$ denotes that the observer is coming towards the police car which is the source of the sound.

Now when, $v_s=50\ m.s^{-1}$

Then, $f_o=?$

Using the Doppler's eq.:

$\frac{f_o}{1200} =\frac{(350+(-29.167))}{(350-50)}$

$f_o=1283.33\ Hz$

3 0

3 years ago

A solar charging system produces 14.5 volts on a sunny day the currents flows through the circuit at 43.5 ramps what is the resi

brilliants [131]

Eeeeeeeeeeeeeeeeeeeee

8 0

3 years ago

A ball rolls down the hill which has a vertical height of 15 m. Ignoring friction what would be the gravitational potential ener

trasher [3.6K]

a) Potential energy: 147 m [J]

The gravitational potential energy of an object is given by

$U=mgh$

where

m is its mass

$g=9.8 m/s^2$ is the acceleration of gravity

h is the height of the object above the ground

In this problem,

h = 15 m

We call 'm' the mass of the ball, since we don't know it

So, the potential energy of the ball at the top of the hill is

$U=(m)(9.8)(15)=147 m$ (J)

b) Velocity of the ball at the bottom of the hill: 17.1 m/s

According to the law of conservation of energy, in absence of friction all the potential energy of the ball is converted into kinetic energy as the ball reaches the bottom of the hill. Therefore we can write:

$U=K=\frac{1}{2}mv^2$

where

v is the final velocity of the ball

We know from part a) that

U = 147 m

Substituting into the equation above,

$147 m = \frac{1}{2}mv^2$

And re-arranging for v, we find the velocity:

$v=\sqrt{2\cdot 147}=17.1 m/s$

5 0

3 years ago

Which component of magma includes mobile ions of silicon?

Lemur [1.5K]

Answer:

Melt.

Explanation:

When rocks melt, they do so slowly and gradually because most rocks are made of several minerals, which all have different melting points; moreover, the physical and chemical relationships controlling the melting are complex. As a rock melts, for example, its volume changes. When enough rock is melted, the small globules of melt link up and soften the rock.

Under normal conditions, mantle rock like peridotite shouldn't melt in the Earth's upper mantle. However, by adding water you can lower the melting point of the rock. Alternatively, by decompressing the rock, you can bring it to a pressure where the melting point is lower. In both cases, basalt magma will form and considering it is hotter and less dense than the surrounding rock, it will percolate towards the surface and some of that erupts.

6 0

3 years ago

A body accelerates uniformly from rest at 2m/s square. calculate it's velocity after traveling 9m.

Talja [164]

Answer:

6m/s

Explanation:

Given parameters:

Initial velocity = 0m/s

Acceleration = 2m/s²

Distance = 9m

Unknown:

Final velocity = ?

Solution:

To solve this problem, we use the expression below:

v² = u² + 2as

v is the final velocity

u is the initial velocity

a is the acceleration

s is the distance

v² = 0² + (2 x 2 x 9) = 36

v = 6m/s

3 0

3 years ago