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3 years ago

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Melissa and Rory live near a bike trail, 21 km apart. They plan to meet at a park mid-way between their homes. They start from t

heir homes at the same moment, and ride toward each other. Both ride at 7 km/hour. Melissa’s dog Jessie knows this routine. He starts with Melissa, and runs at 18 km/hour toward Rory. When he reaches Rory, he turns around and runs toward Melissa. He reaches Melissa, turns around and runs toward Rory again, and so on, until Melissa and Rory meet. How many kilometers did Jessie run?

1 answer:

DiKsa [7]3 years ago

7 0

Answer:

27km.

Explanation:

Jessie will run for a duration of time, which is the time it takes for Melissa and Rory to meet each other.

Together combined, Melissa and Rory runs at 14km/h. The bike trail is 21km, so it will take 1.5 hours.

Jessie runs at 18km/h, so Jessie will run 18 * 1.5 = 27km.

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A 4.67-g bullet is moving horizontally with a velocity of +357 m/s, where the sign + indicates that it is moving to the right (s

Leni [432]

Answer:

(a)0.531m/s

(b)0.00169

Explanation:

We are given that

Mass of bullet, m=4.67 g= $4.67\times 10^{-3} kg$

1 kg =1000 g

Speed of bullet, v=357m/s

Mass of block 1, $m_1=1177g=1.177kg$

Mass of block 2, $m_2=1626 g=1.626 kg$

Velocity of block 1, $v_1=0.681m/s$

(a)

Let velocity of the second block after the bullet imbeds itself=v2

Using conservation of momentum

Initial momentum=Final momentum

$mv=m_1v_1+(m+m_2)v_2$

$4.67\times 10^{-3}\times 357+1.177(0)+1.626(0)=1.177\times 0.681+(4.67\times 10^{-3}+1.626)v_2$

$1.66719=0.801537+1.63067v_2$

$1.66719-0.801537=1.63067v_2$

$0.865653=1.63067v_2$

$v_2=\frac{0.865653}{1.63067}$

$v_2=0.531m/s$

Hence, the velocity of the second block after the bullet imbeds itself=0.531m/s

(b)Initial kinetic energy before collision

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

$k_i=\frac{1}{2}(4.67\times 10^{-3}\times (357)^2)$

$k_i=297.59 J$

Final kinetic energy after collision

$K_f=\frac{1}{2}m_1v^2_1+\frac{1}{2}(m+m_2)v^2_2$

$K_f=\frac{1}{2}(1.177)(0.681)^2+\frac{1}{2}(4.67\times 10^{-3}+1.626)(0.531)^2$

$K_f=0.5028 J$

Now, he ratio of the total kinetic energy after the collision to that before the collision

= $\frac{k_f}{k_i}=\frac{0.5028}{297.59}$

=0.00169

5 0

2 years ago

Answer the question with step.

Maru [420]

Answer:

f1/f2 =W1/W2 = 1/3

.0 f2 = 3f1

As ,

1/F= 1/f1 +1/f2

...1/40 = 1/f1 - 1/3f1

f1=> 80/3 cm

... f2 = 2f1 = 3 x 80/3 = 80 cm

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3 years ago

A boat sails south with the help of a wind blowing in the direction S36°E with magnitude 300 lb. Find the work done by the wind

goldfiish [28.3K]

Answer:

The work done by the wind as the boat moves 130 ft is (rounded) W= 31,550 ft-lb.

Explanation:

F= 300 lb < -54º

Fsouth= 300 lb * cos(36º)

Fsouth= 242.7 lb

d= 130 ft

W= F*d

W= 31551 ft-lb

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2 years ago

__________ is the school of psychology that believes perception is more than the sum of its parts—it involves a whole pattern. A

diamong [38]

Answer:

(D. Gestalt psychology) , is the school of psychology that believes perception is more than the sum of its parts, it involves a whole pattern .

This type of school of psychology studied how all components of sensations are assembled into one's perception .

hope this helps :)

4 0

3 years ago

Read 2 more answers

Your cell phone typically consumes about 390 mW of power when you text a friend. If the phone is operated using a lithium-ion ba

yulyashka [42]

Answer:

I = 0.11 A

Explanation:

In an electric circuit, the power delivered to a load, is just the product of the potential difference between the load terminals, times the current flowing through it, as follows:

$P = V*I$

In this case, the power is the one consumed by the cell phone = 390 mW, and the voltage the one produced by the internal energy of the battery, 3.5 V, neglecting the voltage loss at the internal resistance of the battery.
So, we can solve the above equation for the current I, as follows:

$I = \frac{P}{V} = \frac{0.39W}{3.5V} = 0.11 A$

The current flowing through the cell-phone circuitry is 0.11 A.

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2 years ago