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2 years ago

1.) A stone falls from rest from the top of a cliff.

Physics

1 answer:

KengaRu [80]2 years ago

4 0

Answer:

Explanation:

ignore air resistance

Let t be the time of fall for the dropped stone.

½(9.8)t² = 43.12(t - 2.2) + ½(9.8)(t - 2.2)²

4.9t² = 43.12t - 94.864 + 4.9(t² - 4.4t + 4.84)

4.9t² = 43.12t - 94.864 + 4.9t² - 21.56t + 23.716

0 = 21.56t - 71.148

t = 71.148/21.56 = 3.3 s

h = ½(9.8)3.3² = 53.361 = 53 m

h = 43.12(3.3 - 2.2) + ½(9.8)(3.3 - 2.2)² = 53.361 = 53 m

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2 years ago

If the resultant of two velocity vectors of equal magnitude is also of the same magnitude, then which statement must be correct?

Tamiku [17]

The correct option is C) The angle between the vectors is 120°.

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Have a nice day!

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2 years ago

Which change occurs when an atom undergoes alpha decay?

oee [108]

In an alpha decay, an atom emits an alpha particle. An alpha particle consists of 2 protons and 2 neutrons: this means that during this kind of decay, the original atom loses 2 protons and 2 neutrons from its nucleus.

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2 years ago

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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.

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3 years ago

A 3858 N piano is to be pushed up a(n) 3.49 m frictionless plank that makes an angle of 31.6 ◦ with the horizontal. Calculate th

uranmaximum [27]

The work done will be equal to the potential energy of the piano at the final position

P.E=m.g.h

.consider the plank the hypotenuse of the right triangle formed with the ground
.let x be the angle with the ground=31.6°
.h be the side opposite to the angle x (h is the final height of the piano)
.let L be the length of the plank

sinx=opposite side / hypotenuse
= h/L

then h=L.sinx=3.49×sin31.6°=0.638m

weight w=m.g
m=w/g=3858/10=385.8kg

Consider Gravity g=10m/s2

then P.E.=m.g.h=385.8kg×10×0.638=2461.404J

then Work W=P.E.=2451.404J

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2 years ago

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