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inn [45]
3 years ago
5

A person drives an automobile with a mass of 450 kilograms at a velocity of 26 meters per second. The driver accelerates to a ve

locity of 30 meters per second. The difference in the automobile’s kinetic energy between the two velocities is joules. You may use the calculator.
Physics
1 answer:
gregori [183]3 years ago
7 0

Ec₁=mv₁²/2=450*26²/2=225*676=152100 J

Ec₂=mv₂²/2=450*30²/2=225*900=202500 J

ΔEc=Ec₂-Ec₁=202500-152100=50.4 kJ

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A plastic rod 1.3 m long is rubbed all over with wool, and acquires a charge of -3e-08 coulombs. we choose the center of the rod
Anestetic [448]
(a) The plastic rod has a length of L=1.3m. If we divide by 8, we get the length of each piece:
L/8=1.3m/8=0.1625 m

(b) The center of the rod is located at x=0. This means we have 4 pieces of the rod on the negative side of x-axis, and 4 pieces on the positive side. So, starting from x=0 and going towards positive direction, we have: piece 5, piece 6, piece 7 and piece 8. Each piece is 0.1625 m long. Therefore, the center of piece 5 is at 0.1625m/2=0.0812 m. And the center of piece 6 will be shifted by 0.1625m with respect to this:
c_6 = 0.0812m+0.1625m=0.2437 m

(c) The total charge is Q=-3 \cdot 10^{-8}C. To get the charge on each piece, we should divide this value by 8, the number of pieces:
Q/8=-3\cdot 10^{-8}C/8=-3.75\cdot 10^{-9}C

(d) We have to calculate the electric field at x=0.7 generated by piece 6. The charge on piece 6 is the value calculated at point (c):
q= -3.75\cdot 10^{-9}C
If we approximate piece 6 as a single  charge, the electric field is given by
E=k_e  \frac{q}{d^2}
where k_e=8.99\cdot 10^9Nm^2C^{-2} and d is the distance between the charge (center of piece 6, located at 0.2437m) and point a (located at x=0.7m). Therefore we have
E= 8.99\cdot 10^9 Nm^2C^{-2} \frac{-3.75\cdot 10^9 C}{(0.2437m-0.7m)^2} =-161.9 V/m
poiting towards the center of piece 6, since the charge is negative.

(e) missing details on this question.
5 0
3 years ago
If a magnet could swing freely, what would happen to its north-seeking pole?
maksim [4K]

You clearly identified the pole you're talking about as the
"north-seeking" pole.  Assuming your integrity and sincerity,
we would then naturally expect that pole to seek north, and
point to Earth's north magnetic pole. 

I'm confident in this answer also because I have several of
these devices hanging from the ceiling of my office, and I can
attest to the fact that on most clear days, they do in fact point
toward Earth's north magnetic pole.

8 0
3 years ago
A person with mass mp = 74 kg stands on a spinning platform disk with a radius of R = 2.31 m and mass md = 183 kg. The disk is i
timurjin [86]

Answer:

1) 883 kgm2

2) 532 kgm2

3) 2.99 rad/s

4) 944 J

5) 6.87 m/s2

6) 1.8 rad/s

Explanation:

1)Suppose the spinning platform disk is solid with a uniform distributed mass. Then its moments of inertia is:

I_d = m_dR^2/2 = 183*2.31^2/2 = 488 kgm^2

If we treat the person as a point mass, then the total moment of inertia of the system about the center of the disk when the person stands on the rim of the disk:

I_{rim} = I_d + m_pR^2 = 488 + 74*2.31^2 = 883 kgm^2

2) Similarly, he total moment of inertia of the system about the center of the disk when the person stands at the final location 2/3 of the way toward the center of the disk (1/3 of the radius from the center):

I_{R/3} = I_d + m_p(R/3)^2 = 488 + 74*(2.31/3)^2 = 532 kgm^2

3) Since there's no external force, we can apply the law of momentum conservation to calculate the angular velocity at R/3 from the center:

I_{rim}\omega_{rim} = I_{R/3}\omega_{R/3}

\omega_{R/3} = \frac{I_{rim}\omega_{rim}}{I_{R/3}}

\omega_{R/3} = \frac{883*1.8}{532} = 2.99 rad/s

4)Kinetic energy before:

E_{rim} = I_{rim}\omega_{rim}^2/2 = 883*1.8^2/2 = 1430 J

Kinetic energy after:

E_{R/3} = I_{R/3}\omega_{R/3}^2/2 = 532*2.99^2/2 = 2374 J

So the change in kinetic energy is: 2374 - 1430 = 944 J

5) a_c = \omega_{R/3}^2(R/3) = 2.99^2*(2.31/3) = 6.87 m/s^2

6) If the person now walks back to the rim of the disk, then his final angular speed would be back to the original, which is 1.8 rad/s due to conservation of angular momentum.

3 0
3 years ago
The change in momentum for an object is equal to
koban [17]

Answer:

We conclude that the change in momentum of a body is equal to the impulse experienced by a body.

Explanation:

Considering the equation

F • t = m • Δ v

Here,

m • Δ v is basically a change in momentum of a body which is equal to the mass of the object multiplied by the change in its velocity.

Also,

  • F • t is called the impulse of the object.

In the formula, it is clear that the impulse experienced by a body during the collision is basically a change in the momentum of the body.

In other words, the change in momentum of a body is equal to the impulse experienced by a body.

Therefore, we conclude that the change in momentum of a body is equal to the impulse experienced by a body.

4 0
3 years ago
How to calculate the average velocity, in m/s.
saw5 [17]
Using the average velocity formula which is total distance divided by total time. If the distance is given in km convert to m then divide by 1000 to get m and if time is given in minutes then divide by 60 to get seconds. And after converting, divide to get your final answer in m/s. Hope that helped!
4 0
2 years ago
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