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4 years ago

A train travels 86 kilometers in 1 hours, and then 98 kilometers in 1 hours. What is its average speed?

1 answer:

4 0

Answer: average speed = 92 km/h

Explanation:

1) Data:

distance 1 = 86 km
time 1 = 1 hour

distance 2 = 98 km
time 2 = 1 hour

average speed = ?

2) Formula:

average speed = distance / time

3) distance = distance 1 + distance 2 = 86 km + 98 km = 184 km

4) time = time 1 + time 2 = 1 h + 1 h = 2h

5) average speed = 184 km / 2h = 92 km/h

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Whenever one object exerts a force on another object, the second object exerts a force of the same magnitude on the first object

Naddik [55]

Answer:

Explanation:

Newton third law of motion state that action and reaction are equal and opposite

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3 years ago

) A 73-mH solenoid inductor is wound on a form that is 0.80 m long and 0.10 m in diameter. A coil having a resistance of is tigh

Aleonysh [2.5K]

Complete question is;. A 73mH solenoid inductor is wound on a form that is 0.80m long and 0.10m in diameter a coil having a resistance of 7.7 ohms is tightly wound around the solenoid at its center the mutual inductance of the coil and solenoid is 19μH at a given instant the current in the solenoid is 820mA and is decreasing at the rate of 2.5A/s at the given instant what is the induced current in the coil

Answer:

6.169 μA

Explanation:

Formula for induced EMF is given by the equation;

EMF = M(di/dt). We are given;

di/dt = 2.5 A/s

M = 19μH = 19 × 10^(-6) H

Thus;

EMF = 19 × 10^(-6) × 2.5.

EMF = 47.5 × 10^(-6) V

Formula for current is;

i = EMF/R. R is resistance given as 7.7 ohms.

Thus; i = 47.5 × 10^(-6)/7.7

i = 6.169 μA

5 0

3 years ago

A bat emits a sound at a frequency of 30.0 kHz as it approaches a wall. The bat detects beats such that the frequency of the ech

Alex

Answer:

The speed of the bat is 5.02 m/s.

Explanation:

Given that,

Frequency = 30.0 kHz

Frequency of echo = 900 Hz

We need to calculate the frequency

Using formula of beat frequency

$f_{b}=f_{1}-f_{2}$

Put the value into the formula

$900=f_{1}-30\times10^{3}$

$f_{1}=900+30000$

$f_{1}=30900\ Hz$

We need to calculate the speed of the bat

Using Doppler equation

$f_{apr}=f\times(\dfrac{v_{sound}+v_{observer}}{v_{s}-v_{source}})$

Put the value into the formula

$30900=30000\times(\dfrac{340+v_{bat}}{340-v_{bat}})$

$\dfrac{30900}{30000}=\dfrac{340+v_{bat}}{340-v_{bat}}$

$1.03=\dfrac{340+v_{bat}}{340-v_{bat}}$

$340\times1.03-340=v_{b}+1.03v_{b}$

$10.2=2.03v_{bat}$

$v_{bat}=\dfrac{10.2}{2.03}$

$v_{bat}=5.02\ m/s$

Hence, The speed of the bat is 5.02 m/s.

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3 years ago

and area' Explain the following in your answers, use the words pressure', 'force A truck used in the desert has wide tyres. 6 A

nlexa [21]

Answer:

a cricket stamp

Explanation:

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3 years ago

A dog can hear sounds in the range from 15 to 50,000 hz. what wavelength corresponds to the lower cut-off point of the sounds at

Ira Lisetskai [31]

The frequency corresponding to the lower cut-off point is
$f=15 Hz$
The speed of sound at a temperature of $20^{\circ}C$ is approximately
$v=343 m/s$

Therefore we can use the relationship between speed of a wave, frequency and wavelength to calculate the corresponding wavelength:
$\lambda= \frac{v}{f}= \frac{343 m/s}{15 Hz}=22.87 m$
So, the corresponding wavelength is 22.87 m.

3 0

3 years ago