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3 years ago

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A 60kg student traveling in a 1000kg car with a constant velocity has a kinetic energy of 1.2 x 10^4 J. What is the speedometer

reading of the car in km/hr?

1 answer:

777dan777 [17]3 years ago

4 0

Answer:

17.64 km/h

Explanation:

mass of car, m = 1000 kg

Kinetic energy of car, K = 1.2 x 10^4 J

Let the speed of car is v.

Use the formula for kinetic energy.

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

By substituting the values

$1.2\times 10^{4} = \frac{1}{2}\times 1000\times v^{2}$

v = 4.9 m/s

Now convert metre per second into km / h

We know that

1 km = 1000 m

1 h = 3600 second

So, $v = \left (\frac{4.9}{1000} \right )\times \left ( \frac{3600}{1} \right )$

v = 17.64 km/h

Thus, the reading of speedometer is 17.64 km/h.

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A 310-km-long high-voltage transmission line 2.00 cm in diameter carries a steady current of 1,010 A. If the conductor is copper

Marizza181 [45]

Answer:

t = 166 years

Explanation:

In order to calculate the amount of years that electrons take to cross the complete transmission line. You first calculate the drift speed of the electrons by using the following formula:

$v_d=\frac{I}{nqA}$ (1)

I: current on the wire = 1,010A

n: free charge density = 8.50*10^28 electrons/m^3

A: cross-sectional area of the transmission line = π*r^2

r: radius of the cross-sectional area = 2.00cm = 0.02m

You replace the values of the parameters in the equation (1):

$v_d=\frac{1,010A}{(8.50*10^{28}electron/m^3)(1.6*10^{-19}C)(\pi (0.02m)^2)}\\\\v_d=5.9*10^{-5}\frac{m}{s}$

Next, you use the following formula:

$t=\frac{x}{v_d}$ (2)

x: length of the line transmission = 310km = 310,000m

You replace the values of vd and x in the equation (2):

$t=\frac{310,000m}{5.9*10^{-5}m/s}=5.24*10^9s$

Finally, you convert the obtained t to seconds

$t=5.24*10^9s*\frac{1\ year}{3.156*10^7s}=166.03\ years$

The electrons take approximately 166 years to travel trough the complete transmission line

5 0

3 years ago

What is the threshold velocity vthreshold(water) (i.e., the minimum velocity) for creating Cherenkov light from a charged partic

VladimirAG [237]

Complete Question

The complete question is shown on the first uploaded image

Answer:

A

$v_w = 2.256 *10^{8} \ m/s$

B

$v_e = 2.21 *10^{8} \ m/s$

C

The correct option is B

Explanation:

From the question we are told that

The refractive index of water is $n_w = 1.33$

The refractive index of ethanol is $n_e = 1.36$

Generally the threshold velocity for creating Cherenkov light from a charged particle as it travels through water is mathematically evaluated as

$v_w = \frac{c}{n_w }$

Where c is the speed of light with value $c = 3.0 *10^{8} \ m/s$

$v_w = \frac{3.0 *10^{8}}{1.33 }$

$v_w = 2.256 *10^{8} \ m/s$

Generally the threshold velocity for creating Cherenkov light from a charged particle as it travels through water is mathematically evaluated as

$v_e = \frac{ c}{n_e }$

=> $v_e = \frac{3.0 *10^{8}}{1.36 }$

=> $v_e = 2.21 *10^{8} \ m/s$

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3 years ago

Can someone please explain to me why the net force of the ball changes in the Y direction and not the X Direction? I made little

stiks02 [169]

Whenever an object is in projectile motion, that is, it has 2-dimensional motion in the x and y axis, the resultant force on the object is in the y-direction.
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However, the force of gravity cannot be neglected and causes the ball to come downwards. Therefore, after the ball has been projected, the net force on the ball is downwards, due to gravity.

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3 years ago

When I wave a charged golf tube at the front of the classroom with a frequency of two oscillations per second, I produce an elec

borishaifa [10]

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From the definition we know that the wavelength is described under the equation,

$\lambda = \frac{c}{f}$

Where,

c = Speed of light (vacuum)

f = frequency

Our values are,

$f = 2Hz$

$c = 3*10^8km/s$

Replacing we have,

$\lambda = \frac{c}{f}$

$\lambda = \frac{3*10^8km/s}{2Hz}$

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3 years ago

A 878-kg (1940 lb) dragster, starting from rest, attains a speed of 25.9 m/s (57.9 mph) in 0.62 s. (a) Find the average accelera

salantis [7]

Answer:

41.8m/s^2

Explanation:

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3 years ago