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3 years ago

I have two questions I need help with.

1 answer:

4 0

1). The Earth would need much much much much much more mass than it has in order to see any change in our orbital period around the sun. An increase of 20% won't jhave any effect.

3). This question isn't clear. "years" isn't a unit of length or distance. It can't describe a change in our distance from the sun, so we don't know what this question is actually asking.

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The platform height for Olympic divers is 10 m. A 60 kg diver steps off the platform to begin his dive.

azamat

Answer:

a) Ep = 5886[J]; b) v = 14[m/s]; c) W = 5886[J]; d) F = 1763.4[N]

Explanation:

The potential energy can be found using the following expression, we will take the ground level as the reference point where the potential energy is equal to zero.

$E_{p} =m*g*h\\where:\\m = mass = 60[kg]\\g = gravity = 9.81[m/s^2]\\h = elevation = 10 [m]\\E_{p}=60*9.81*10\\E_{p}=5886[J]$

Since energy is conserved, that is, potential energy is transformed into kinetic energy, the moment the harpsichord touches water, all potential energy is transformed into kinetic energy.

$E_{p} = E_{k} \\5886 =0.5*m*v^{2} \\v = \sqrt{\frac{5886}{0.5*60} }\\v = 14[m/s]$

The work is equal to

W = 5886 [J]

We need to use the following equation and find the deceleration of the diver at the moment when he stops his velocity is zero.

$v_{f} ^{2}= v_{o} ^{2}-2*a*d\\where:\\d = 2.5[m]\\v_{f}=0\\v_{o} =14[m/s]\\Therefore\\a = \frac{14^{2} }{2*2.5} \\a = 39.2[m/s^2]$

By performing a sum of forces equal to the product of mass by acceleration (newton's second law), we can find the force that acts to reduce the speed of the diver to zero.

m*g - F = m*a

F = m*a - m*g

F = (60*39.2) - (60*9.81)

F = 1763.4 [N]

3 0

3 years ago

A woman is 160160cm tall. What is the minimum vertical length of a mirror in which she can see her entire body while standing up

kipiarov [429]

This question is incomplete, the complete question is;

A woman is 160cm tall. What is the minimum vertical length of a mirror in which she can see her entire body while standing upright.

Hint: Consider the ray diagram below, of the rays that enable her to see her feet and the top of her head.

Use what you know about the law of reflection, together with a bit geometry.

The missing Image is uploaded along this answer below.

Answer:

the minimum vertical length of a mirror in which she can see her entire body while standing upright is 80 cm

Explanation:

Given the data in the question and illustrated in the image below,

From image 2;

The distance from the woman's eyes to the top of her head is represented as b and a represent the distance from her eyes to her feet.

Therefore, since her height is 160 cm

a + b = 160 ------ let this be equation 1

i.e AD + DG = 160 cm

Now, from the same image 2, we will notice that triangle ABC and tringle CBD are similar, so

∠ABC = ∠CBD

AC = CD

since AD = a and AC + CD = A

AC = CD = a/2

Also, triangle DEF and FEG are si,ilar

∠DEF = ∠FEG

DF = FG

since DG = b and DF + FG = b

DF = b/2

so the minimum vertical length of a mirror in which the woman can see her entire body while standing upright will be;

⇒ a/2 + b/2

⇒ a + b / 2

from equation 1, a + b = 160

⇒ a + b / 2 = 160 / 2 = 80

Therefore, the minimum vertical length of a mirror in which she can see her entire body while standing upright is 80 cm

4 0

3 years ago

7. Katie and her best friend Liam play tennis every Saturday morning. When Katie serves the ball to Liam, it

KIM [24]

a. 4.52 m/s south

Velocity is a vector, whose magnitude is defined as the ratio between the displacement of the object and the time taken for the displacement to occur:

$v=\frac{d}{t}$

where

d is the displacement

t is the time

Velocity is a vector, so it also has a direction, which corresponds to that of the displacement.

For the ball in this problem,

d = 9.5 m south

t = 2.1 s

Substituting, we find:

$v=\frac{9.5}{2.1}=4.52 m/s$

and the directiion is the same as the displacement (south).

b. 4.52 m/s north

For this part, we must keep in mind that the speed is the magnitude of the velocity; however, speed is a scalar, so it does not have a direction.

Here we are told that the tennis ball travels at constant speed, so on its way back from Liam to Katie the ball's velocity is still the same as before, therefore

$|v| = 4.52 m/s$

However, this time the direction is opposite to before, since the ball is travelling in the opposite direction.

Therefore, the ball's velocity when Liam returns Katie's service is

4.52 m/s north

8 0

3 years ago

If there is no friction in a rollercoaster is the speed the same throughout?

andrey2020 [161]

If there is no friction, the roller coaster would keep moving forever but a constant velocity. The only way it would accelerate is if there was a force continually pushing on it.

4 0

3 years ago

Read 2 more answers

On planet X, an object weighs 7.04 N. Onplanet B where the magnitude of the free-fallacceleration is 1.91g(whereg= 9.8 m/s2isthe

timurjin [86]

<h2>Mass of object in Earth is 1.37 kg</h2>

Explanation:

On planet B where the magnitude of the free-fall acceleration is 1.91g , the object weighs 25.74 N.

We have

Weight = Mass x Acceleration due to gravity

On planet B

25.74 = Mass x 1.91 g

25.74 = Mass x 1.91 x 9.81

Mass = 1.37 kg

Mass is constant for an object. It will not change with location.

Mass of object in Earth = Mass of object in Planet B

Mass of object in Earth = 1.37 kg

4 0

3 years ago