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3 years ago

6

Which of the following is the brightness of a star as we see if from Earth?

1 answer:

My name is Ann [436]3 years ago

8 0

I think that it is apparent magnitude

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A 30 kg mass and a 20 kg mass are joined by a light rigid rod and this system is free to rotate in the plane of the page about a

stepan [7]

55 J

Explanation:

Kinetic energy is given as: 0.5MV^2 where M is the mass and V is the speed of rotation. Since the masses are point masses, we calculate the point mass for each mass.

M1 = 30*0.2^2 = 1.2kgm^2

M2 = 20*0.4^2 = 3.2kgm^2

V = 5 rad/s

Calculating using the formula above, we obtain :

0.5(1.2+3.2)5^2 =0.5*4.4*25 = 55 J

3 0

3 years ago

Read 2 more answers

If you know the distance an object has traveled in a certain amount of time you can determine

Nutka1998 [239]

With that information, you can determine the object's speed.
Just divide the distance covered by the time to cover the distance.

If you also know the direction the object moved, then you can
determine its velocity. If you don't, then you can't.

5 0

4 years ago

Read 2 more answers

A 0.150 kg stone rests on a frictionless, horizontal surface. A bullet of mass 9.50 g, traveling horizontally at 380 m/s, strike

Anvisha [2.4K]

Answer:

(a)Magnitude=28.81 m/s

Direction=33.3 degree below the horizontal

(b) No, it is not perfectly elastic collision

Explanation:

We are given that

Mass of stone, M=0.150 kg

Mass of bullet, m=9.50 g= $9.50\times 10^{3} kg$

Initial speed of bullet, u=380 m/s

Initial speed of stone, U=0

Final speed of bullet, v=250m/s

a. We have to find the magnitude and direction of the velocity of the stone after it is struck.

Using conservation of momentum

$mu+ MU=mv+ MV$

Substitute the values

$9.5\times 10^{-3}\times 380 i+0.150(0)=9.5\times 10^{-3} (250)j+0.150V$

$3.61i=2.375j+0.150V$

$3.61 i-2.375j=0.150V$

$V=\frac{1}{0.150}(3.61 i-2.375j)$

$V=24.07i-15.83j$

Magnitude of velocity of stone

= $\sqrt{(24.07)^2+(-15.83)^2}$

|V|=28.81 m/s

Hence, the magnitude and direction of the velocity of the stone after it is struck, |V|=28.81 m/s

Direction

$\theta=tan^{-1}(\frac{y}{x})$

= $tan^{-1}(\frac{-15.83}{24.07})$

$\theta=tan^{-1}(-0.657)$

=33.3 degree below the horizontal

(b)

Initial kinetic energy

$K_i=\frac{1}{2}mu^2+0=\frac{1}{2}(9.5\times 10^{-3})(380)^2$

$K_i=685.9 J$

Final kinetic energy

$K_f=\frac{1}{2}mv^2+\frac{1}{2}MV^2$

= $\frac{1}{2}(9.5\times 10^{-3})(250)^2+\frac{1}{2}(0.150)(28.81)^2$

$K_f=359.12 J$

Initial kinetic energy is not equal to final kinetic energy. Hence, the collision is not perfectly elastic collision.

5 0

3 years ago

A baseball with a mass of 0.80 kg is given an acceleration of 20.00 m/s. How much net force was applied to the ball

dybincka [34]

a x m = f

.80 x 20 = 16

4 0

3 years ago

A middle-A tuning fork vibrates with a frequency f of 440 hertz (cycles per second). You strike a middle-A tuning fork with a fo

jeyben [28]

Answer:

P = 5sin(880πt)

Explanation:

We write the pressure in the form P = Asin2πft where A = amplitude of pressure, f = frequency of vibration and t = time.

Now, striking the middle-A tuning fork with a force that produces a maximum pressure of 5 pascals implies A = 5 Pa.

Also, the frequency of vibration is 440 hertz. So, f = 440Hz

Thus, P = Asin2πft

P = 5sin2π(440)t

P = 5sin(880πt)

3 0

3 years ago