Which one of the following choices is an effective way to pervent low-back pain

Which image illustrates the bouncing of a light wave off of a surface?

Naily [24]

Answer:

The answer is A good luck :P

8 0

3 years ago

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A projectile is launched straight up from a height of 960 feet with an initial velocity of 64 ft/sec. Its height at time t is h(

Natasha2012 [34]

Answer:

a) $t=2s$

b) $h_{max}=1024ft$

c) $v_{y}=-256ft/s$

Explanation:

From the exercise we know the initial velocity of the projectile and its initial height

$v_{y}=64ft/s\\h_{o}=960ft\\g=-32ft/s^2$

To find what time does it take to reach maximum height we need to find how high will it go

b) We can calculate its initial height using the following formula

Knowing that its velocity is zero at its maximum height

$v_{y}^{2}=v_{o}^{2}+2g(y-y_{o})$

$0=(64ft/s)^2-2(32ft/s^2)(y-960ft)$

$y=\frac{-(64ft/s)^2-2(32ft/s^2)(960ft)}{-2(32ft/s^2)}=1024ft$

So, the projectile goes 1024 ft high

a) From the equation of height we calculate how long does it take to reach maximum point

$h=-16t^2+64t+960$

$1024=-16t^2+64t+960$

$0=-16t^2+64t-64$

Solving the quadratic equation

$t=\frac{-b±\sqrt{b^{2}-4ac}}{2a}$

$a=-16\\b=64\\c=-64$

$t=2s$

So, the projectile reach maximum point at t=2s

c) We can calculate the final velocity by using the following formula:

$v_{y}^{2}=v_{o}^{2}+2g(y-y_{o})$

$v_{y}=±\sqrt{(64ft/s)^{2}-2(32ft/s^2)(-960ft)}=±256ft/s$

Since the projectile is going down the velocity at the instant it reaches the ground is:

$v=-256ft/s$

5 0

2 years ago

The potential energy of a pair of hydrogen atoms separated by a large distance x is given by U(x)=−C6/x6, where C6 is a positive

kirza4 [7]

Answer:

The correct answer will be " $-\frac{6C_{6}}{x^{7}}$ ". The further explanation is given below.

Explanation:

The potential energy will be,

⇒ $U(x)= -\frac{C_{6}}{x^6}$

The expression of force will be,

⇒ $F=-\frac{dU(x)}{dx}$

⇒ $=-(C_{6}(-6)x^{-7})$

⇒ $=-\frac{6C_{6}}{x^{7}}$

Force seems to be appealing because the expression has been negative. It therefore means that the force or substance is acting laterally in on itself.

6 0

3 years ago

Your boat departs from the bank of a river that has a swift current parallel to its banks. If you want to cross this river in th

REY [17]

Answer:

D.

Explanation:

Given that your boat departs from the bank of a river that has a swift current parallel to its banks. If you want to cross this river in the shortest amount of time, you should direct your boat: so that it drifts with the current.

If the boat moves perpendicular to the current, the current flow will be the resistance to the movement of the boat. So, it's better for the boat to drifts perpendicularly with the current.

The best answer is therefore option D.

8 0

3 years ago

A slug has a speed of .00242 miles per hour

Delvig [45]

I like fortnite too:):):)

4 0

3 years ago