Find the mass of a ball if it was thrown with a force of 18N and 2m/s2

Which of these phase changes requires energy?

frutty [35]

Answer:

A

Explanation:

You have to give energy away for B. You have to think about that carefully. The CO2 starts out with a great deal of energy (mostly KE) and has to slow down to go from gas to a solid. Not B

In general C is the same way. Water has more energy than ice. Not C

Same principle in D. Not D.

So it's A

7 0

1 year ago

A mass weighing 32 pounds stretches a spring 2 feet. Determine the amplitude and period of motion if the mass is initially relea

grandymaker [24]

A mass weighing 32 pounds stretches a spring 2 feet.

(a) Determine the amplitude and period of motion if the mass is initially released from a point 1 foot above the equilibrium position with an upward velocity of 6 ft/s.

(b) How many complete cycles will the mass have completed at the end of 4 seconds?

Answer:

$A = 1.803 ft$

Period = $\frac{\pi}{2}$ seconds

8 cycles

Explanation:

A mass weighing 32 pounds stretches a spring 2 feet;

it implies that the mass (m) = $\frac{w}{g}$

m= $\frac{32}{32}$

= 1 slug

Also from Hooke's Law

2 k = 32

k = $\frac{32}{2}$

k = 16 lb/ft

Using the function:

$\frac{d^2x}{dt} = - 16x\\\frac{d^2x}{dt} + 16x =0$

$x(0) = -1$ (because of the initial position being above the equilibrium position)

$x(0) = -6$ ( as a result of upward velocity)

NOW, we have:

$x(t)=c_1cos4t+c_2sin4t\\x^{'}(t) = 4(-c_1sin4t+c_2cos4t)$

However;

$x(0) = -1$ means

$-1 =c_1\\c_1 = -1$

$x(0) =-6$ also implies that:

$-6 =4(c_2)\\c_2 = - \frac{6}{4}$

$c_2 = -\frac{3}{2}$

Hence, $x(t) =-cos4t-\frac{3}{2} sin 4t$

$A = \sqrt{C_1^2+C_2^2}$

$A = \sqrt{(-1)^2+(\frac{3}{2})^2 }$

$A=\sqrt{\frac{13}{4} }$

$A= \frac{1}{2}\sqrt{13}$

$A = 1.803 ft$

Period can be calculated as follows:

= $\frac{2 \pi}{4}$

= $\frac{\pi}{2}$ seconds

How many complete cycles will the mass have completed at the end of 4 seconds?

At the end of 4 seconds, we have:

$x* \frac{\pi}{2} = 4 \pi$

$x \pi = 8 \pi$

$x=8$ cycles

5 0

2 years ago

Which statements describe elements? Check all that apply.

solmaris [256]

The answers are B, C, E and F.

Atoms from an element is mostly made of protons, neutrons, and electrons. Proton numbers are like a class number for each element. Each element has their own and they're all different. And the number of protons are equal to the number of electrons. Therefore, B is correct.

Isotopes. It's different atoms from a same element that has the same number of protons but different number of neutrons. For example in hydrogen, there's 3 Isotopes for hydrogen. Therefore, C is correct.

Again, proton for the same element is never changed, even if they're different Isotopes. So, E is correct.

Isotopes, again, different elements may have different Isotopes. Some has only 1, others may have a few or more. So, F is correct too.

8 0

3 years ago

Read 2 more answers

Which two statements are true about a system?

weqwewe [10]

Answer:The correct options are:

1. A system is a group of objects analyzed as one unit.

2. Energy that moves across system boundaries is conserved.

Explanation:

A system is defined as group of interrelated or interacting items existing as a single unit or a whole to achieve a specific objective.Energy lost by the system is equal to the energy gained by the surroundings.

Two statements are true about a system: