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2 years ago

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Three cars are tested in a 16 m/s frontal crash. The results of the crash tests are shown below, with data indicating how much t

he crumple zone and safety cell of each car deformed. In each car the dummy was secured by the same seat belt and airbag. Which car did the best job of protecting the dummy?

1 answer:

rosijanka [135]2 years ago

4 0

Answer:

Car C

Explanation:

The length of the deformed crumple zone is significantly longer in Car C, so the average deceleration was lower. The lower acceleration puts less stress on the dummy. Car C better protected the dummy.

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Case 1: A DJ starts up her phonograph player. The turntable accelerates uniformly from rest, and takes t₁ = 11.9 seconds to get

olga_2 [115]

Answer:

Part a)

$\omega = 8.17 rad/s$

Part b)

$N = 7.74 rev$

Part c)

$\alpha = 0.69 rad/s^2$

Part d)

$\alpha = 0.48 rad/s^2$

Part e)

$t = 9.14 s$

Explanation:

Part a)

Angular speed is given as

$\omega = 2\pi f$

$\omega = 2\pi(\frac{78}{60})$

$\omega = 8.17 rad/s$

Part b)

Since turn table is accelerating uniformly

so we will have

$\theta = \frac{\omega_f + \omega_i}{2} t$

$\theta = \frac{8.17 + 0}{2}(11.9)$

$2N\pi = 48.6$

$N = 7.74 rev$

Part c)

angular acceleration is given as

$\alpha = \frac{\omega_f - \omega_i}{t}$

$\alpha = \frac{8.17 - 0}{11.9}$

$\alpha = 0.69 rad/s^2$

Part d)

When its angular speed changes to 120 rpm

then we will have

$\omega_2 = 2\pi (\frac{120}{60})$

$\omega_2 = 12.56 rad/s$

number of turns revolved is 15 times

so we have

$\omega_f^2 - \omega_i^2 = 2 \alpha \theta$

$12.56^2 - 8.17^2 = 2\alpha (2\pi\times 15)$

$\alpha = 0.48 rad/s^2$

Part e)

now for uniform acceleration we have

$\omega_f - \omega_i = \alpha t$

$12.56 - 8.17 = 0.48 t$

$t = 9.14 s$

7 0

2 years ago

Air at 27 ºC and 5 atm is throttled by a valve to 1 atm. If the valve is adiabatic and the change in kinetic energy is negligibl

Citrus2011 [14]

Answer:

27 °C

Explanation:

BY the statement of the question it is clear that it is about an ideal gas - and hence if change in KE is about zero - then there will be no change of temperature.

So, answer is 27 °C

4 0

2 years ago

Two people are talking at a distance of 3.0 m from where you are and you measure the sound intensity as 1.1 × 10-7 W/m2. Another

ioda

Answer:

$6.1875\times 10^{-8}$

Explanation:

Assuming uniform spread of sound with no significant reflections or absorption. We know that sound intensity varies $I=\frac {k}{r^{2}}$ where r is the distance

Since intensity is given then when at 3 m

$1.1\times 10^{-7}= \frac {k}{3^{2}}$

$k=3^{2}\times 1.1\times 10^{-7}= 9.9\times 10^{-7}$

Since we have the constant then at 4m

Intensity, $I= \frac {9.9\times 10^{-7}}{4^{2}}=6.1875\times 10^{-8}$

8 0

2 years ago

5. A wave with peaks separated by .34 m has a wavelength of ________________m.

Eduardwww [97]

Answer: 0.17 I think

Explanation:

I asked a doctor

8 0

2 years ago

A teacher is demonstrating energy transformation with a basketball. He drops the ball from a fixed height and challenges his stu

Luda [366]

The ball will bounce at a height lower than the height it was dropped.

Answer: Option B.

<u>Explanation:</u>

When a basket ball is thrown from a particular height, it bounces back. But the height it bounces back at is not exactly the same height from where it was thrown.

With further bounces, the energy of the basket ball goes on decreasing and the bounces go on getting smaller. This shows that there is a change in the energy of the basket ball with every bounce that the ball makes. Some energy lost from the ball gets absorbed by the court and some of the energy is changed into thermal energy.

5 0

2 years ago