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3 years ago

Select the correct answer.

Physics

2 answers:

Angelina_Jolie [31]3 years ago

6 0

Answer:

B. 2 Hours

Explanation:

If your going at a constant speed of 45 miles per hour then, it will take two hours because 45x2 is 90. and if you divided 90 and 45, you will get 2.

Pepsi [2]3 years ago

4 0

Answer:

B. 2 hours

Explanation:

45 miles an hour times 2 is 90 miles in 2 hours

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To stretch a certain nonlinear spring by an amount x requires a force F given by F = 40 x − 6 x 2 , where F is in Newtons and x

strojnjashka [21]

Answer:

64 J

Explanation:

The potential energy change of the spring ∆U = -W where W = work done by force, F.

Now W = ∫F.dx

So, ∆U = - ∫F.dx = - ∫Fdxcos180 (since the spring force and extension are in opposite directions)

∆U = - ∫-Fdx

= ∫F.dx

Since F = 40x - 6x² and x moves from x = 0 to x = 2 m, we integrate thus, ∆U = ∫₀²F.dx

= ∫₀²(40x - 6x²).dx

= ∫₀²(40xdx - 6x²dx)

= ∫₀²(40x²/2 - 6x³/3)

= ∫₀²(20x² - 2x³)

= [20x² - 2x³]₀²

= [(20(2)² - 2(2)³) - (20(0)² - 2(0)³)

= [(20(4) - 2(8)) - (0 - 0))

= [80 - 16 - 0]

= 64 J

5 0

3 years ago

A bowling ball is rolling in a straight line toward the pins at a speed of 2.2 m/s. Its momentum is 4.75 kg*m/s. What is the

Thepotemich [5.8K]

Answer: m= 2.16 kg

Explanation: Momentum is expressed in the following formula:

p = mv

Derive to find m:

m = p / v

= 4.75 kg.m/s / 2.2 m/s

= 2.16 kg

Cancel out m/s and the remaining unit is in kg.

3 0

3 years ago

Read 2 more answers

A scientist is studying the effect on human health of bacteria that live in the human intestine. In her study, she found that th

irga5000 [103]

70 is the correct awnser

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3 years ago

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A rocket of mass 1000kg uses 5kg of fuel and oxygen to produce exhaust gases ejected at 500m/s calculate the increase its veloci

Vlad [161]

Answer:

Approximately $\rm 2.5\; m \cdot s^{-1}$ .

Explanation:

Let the increase in the rocket's velocity be $\Delta v$ . Let $v_0$ represent the initial velocity of the rocket. Note that for this question, the exact value of $v_0$ doesn't really matter.

The momentum of an object is equal to its mass times its velocity.

Mass of the rocket with the 5 kg of fuel: $1000$ .
Initial velocity of the rocket and the fuel: $v_0$ .
Hence the initial momentum of the rocket: $1000\,v_0$ .

Mass of the rocket without that 5 kg of fuel: $1000 - 5 = 995$ .
Final velocity of the rocket: $v_0 + \Delta v$ .
Hence the final momentum of the rocket: $995\,(v_0 + \Delta v)$ .

Mass of the 5 kg of fuel: $5$ .
Final velocity of the fuel: $v_0 - 500$ (assuming that the the 500 m/s in the question takes the rocket as its reference.)
Hence the final momentum of the fuel: $5\,(v_0 - 500)$ .