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kolezko [41]
3 years ago
6

The electric motor of a model train accelerates the train from rest to 0.620 m/s in 21ms. The total mass of the train is 825 g.

find the average power delivered to the train during its acceleration.
Physics
1 answer:
Rudiy273 years ago
7 0

Explanation:

Average power = change in energy / change in time

P = ΔE / Δt

P = (½ mv²) / t

P = (½ (0.825 kg) (0.620 m/s)²) / (0.021 s)

P = 7.55 Watts

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A 0.0382-kg bullet is fired horizontally into a 3.78-kg wooden block attached to one end of a massless, horizontal spring (k = 8
wel

Answer:

280.87 ms⁻¹

Explanation:

Consider the motion of the bullet-block combination after collision

m = mass of the bullet = 0.0382 kg

M = mass of wooden block = 3.78 kg

V = velocity of the bullet-block combination after collision

k = spring constant of the spring = 833 N m⁻¹

A = Amplitude of oscillation = 0.190 m

Using conservation of energy

Kinetic energy of  bullet-block combination after collision = Spring potential energy gained due to compression of spring

(0.5)(m + M)V^{2} = (0.5)kA^{2}

(0.0382 + 3.78)V^{2} = (833)(0.190)^{2}

V = 2.81 ms⁻¹

v_{o} = initial velocity of the bullet before striking the block

Using conservation of momentum for the collision between bullet and block

m v_{o} = (m + M) V

(0.0382) v_{o} = (0.0382 + 3.78) (2.81)

v_{o} = 280.87 ms⁻¹

7 0
3 years ago
A car is designed to get its energy from a rotating
nydimaria [60]

Answer:

(a). The kinetic energy stored in  the fly wheel is 46.88 MJ.

(b). The time is 1.163 hours.

Explanation:

Given that,

Radius = 1.50 m

Mass = 475 kg

Power P= 15.0 hp = 15.0\times746=11190 watt

Rotational speed = 4000 rev/min

We need to calculate the moment of inertia

Using formula of moment of inertia

I=\dfrac{1}{2}mr^2

Put the value into the formula

I=\dfrac{1}{2}\times475\times(1.50)^2

I=534.375\ kg m^2

(a). We need to calculate the kinetic energy stored in  the fly wheel

Using formula of K.E

K.E=\dfrac{1}{2}I\omega^2

Put the value into the formula

K.E = \dfrac{1}{2}\times534.375\times(4000\times\dfrac{2\pi}{60})^2

K.E=46880620.9\ J

K.E =46.88\times10^{6}\ J

K.E =46.88\ MJ

(b). We need to calculate the length of time the car could run before the flywheel  would have to be brought backup to speed

Using formula of time

t=\dfrac{46.88\times10^{6}}{11190}

t=4189.45\ sec

t=1.163\ hours

Hence, (a). The kinetic energy stored in  the fly wheel is 46.88 MJ.

(b). The time is 1.163 hours.

3 0
3 years ago
What is the difference between circumstances and circumference??<br><br>pls ans asap​
dimulka [17.4K]

Answer:

understand

Explanation:

hiiiiiiiiiiiiiiiiiiii

6 0
3 years ago
A falling object accelerates from -10.0 m/s to -30.0 m/s. how much time does it take?
Zepler [3.9K]

Answer:

2.04 s

Explanation:

v = at + v₀

(-30.0 m/s) = (-9.8 m/s²) t + (-10.0 m/s)

t = 2.04 s

8 0
4 years ago
Read 2 more answers
- What are (a) the x component, (b) the y component, and (c) the z component of r = a - b +c if a= 7.8 + 6.6 - 7.1 , b= -2.9 + 7
frez [133]

Answer:

Explanation:

a= 7.8i + 6.6j - 7.1k

b=   -2.9 i+ 7.4 j+ 3.9k , and

c = 7.6i + 8.8j + 2.2k

r = a - b +c

=7.8i + 6.6j - 7.1k - ( -2.9i + 7.4j+ 3.9k )+ ( 7.6i + 8.8j + 2.2k)

= 7.8i + 6.6j - 7.1k +2.9i - 7.4j- 3.9k )+  7.6i + 8.8j + 2.2k

= 18.3 i +18.3 j - k

the angle between r and the positive z axis.

cosθ = 18.3 / √18.3² +18.3² +1

the angle between r and the positive z axis.

= 18.3 / 25.75

cos θ= .71

45 degree

6 0
3 years ago
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