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Ivahew [28]
3 years ago
5

Calculate the size of the image of a tree that is 8m high and 80 m a pinhole camera that is 20 cm long . what is its magnificati

on?
Physics
1 answer:
Vladimir79 [104]3 years ago
4 0

1) Size of the image: 2 cm

In order to calculate the size of the image, we can use the following proportion:

p:q = h_o : h_i

where

p = 80 m is the distance of the tree from the pinhole

q = 20 cm = 0.2 m is the distance of the image from the pinhole

h_o = 8 m is the heigth of the object

h_i is the height of the image

By re-arranging the proportion, we find

h_i = \frac{h_o \cdot q}{p}=\frac{(8 m)(0.2 m)}{80 m}=0.02 m=2 cm


2) Magnification: 0.0025

The magnification of a camera is given by the ratio between the size of the image and the size of the real object:

M=\frac{h_i}{h_o}

so, in this problem we have

M=\frac{0.02 m}{8 m}=0.0025


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A tennis ball (m=0.060 kg) is moving horizontally at 20 m/s toward a tennis player who hits it straight back at 26 m/s. What is
Rus_ich [418]

Answer:

0.36 kg-m/s

Explanation:

Given that,

Mass of a ball, m = 0.06 kg

Initial velocity of the ball, u = 20 m/s

Final velocity of the ball, v = 26 m/s

We need to find the change in momentum of the tennis ball. It is equal to the final momentum minus initial momentum

\Delta p=m(v-u)\\\\=0.06\times (26-20)\\\\=0.36\ kg-m/s

So, the change in momentum of the ball is 0.36 kg-m/s.

4 0
2 years ago
Hey guys can you help me solve this problem "how long will it take a car travelling 30m/s to come to stop ifs its acceleration i
salantis [7]

Answer:

10 seconds.

Explanation:

We can use a kinematic equation where we know the final velocity, initial velocity, acceleration, and need to determine the time <em>t: </em>

<em />\displaystyle v_f = v_i + at<em />

<em />

The initial velocit is 30 m/s, the final velocity is 0 m/s (as we stopped), and the acceleration is -3 m/s².

Substitute and solve for <em>t: </em>

<em />\displaystyle \begin{aligned} (0\text{ m/s}) & = (30 \text{ m/s}) + (-3 \text{ m/s$^2$}) t \\ \\  t & = \frac{-30\text{ m/s}}{-3 \text{ m/s$^2$}} \\ \\ & = 10 \text{ s} \end{aligned}<em />

<em />

Hence, it will take the car 10 seconds to come to a stop.

7 0
2 years ago
What grade of sprain is a completely torn ligament?
Alex Ar [27]
Grade 1: Stretching or slight tearing of the ligament with mild tenderness, swelling and stiffness. The ankle feels stable and it is usually possible to walk with minimal pain.

Grade 2: A more severe sprain, but incomplete tear with moderate pain, swelling and bruising. Although it feels somewhat stable, the damaged areas are tender to the touch and walking is painful.

Grade 3: This is a complete tear of the affected ligament(s) with severe swelling and bruising. The ankle is unstable and walking is likely not possible because the ankle gives out and there is intense pain.

source - https://www.rushcopley.com/health/physician-articles/varying-degrees-of-ankle-sprains/
6 0
3 years ago
a mass of 0.75 kg is attached to a spring and placed on a horizontal surface. the spring has a spring constant of 180 N/m, and t
Artemon [7]

Answer:

6.57 m/s

Explanation:

First use Hook's Law to determine the F the compressed spring acts on the mass. Hook's Law F=kx; F=force, k=stiffnes of spring (or spring constant), x=displacement

F=kx; F=180(.3) = 54 N

Next from Newton's second law find the acceleration of the mass.

Newton's .2nd law F=ma; a=F/m ; a=54/.75 = 72m/s²

Now use the kinematic equation for velocity (or speed)

v₂²= v₀² + 2a(x₂-x₀); v₂=final velocity; v₀=initial velocity; a=acceleration; x₂=final displacement; x₀=initial displacment.

v₀=0, since the mass is at rest before we release it

a=72 m/s² (from above)

x₀=0 as the start position already compressed

x₂=0.3m (this puts the spring back to it's natural length)

v₂²= 0 + 2(72)(0.3) = 43.2 m²/s²

v₂=\sqrt{43.2)\\ = 6.57 m/s

5 0
3 years ago
During convection, heat warms up a fluid, making the fluid less dense so it begins to RISE. As the warm fluid moves, it begins t
Fiesta28 [93]

Answer:

True

Explanation:

Convection is a form of heat transfer that is predominantly common in fluids especially liquid and gas.

It occurs by the movement of a part of substance from one place to another based on density and temperature differences.

A typical convection cell is made up of a liquid that is heated. The liquid part close to the heat source becomes warmer and rises due to its low density. The part away from the heat source is more dense and begins to sink.

This analogy is commonly demonstrated in a boiling pot of water.

7 0
3 years ago
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