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Vanyuwa [196]
3 years ago
13

Suppose you are 80 cm from a plane mirror. What area of the mirror is used to reflect the rays entering one eye from a point on

the tip of your nose if your pupil diameter is 6.7 mm ?
Physics
1 answer:
Stells [14]3 years ago
8 0

Answer:

area = 3.5238 ×10^{-5} m²

Explanation:

Given data

distance = 80 cm

diameter = 6.7 mm

to find out

area of the mirror

solution

we know that by similar triangles

diameter of the spot is use by mirror

so

we calculate radius by diameter is 6.7 mm

so radius = 6.7 /2 = 3.35 mm

radius = 0.00335 m

so

area = πr²

area = π(0.00335)²

area = 3.5238 ×10^{-5} m²

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Oxygen Bleach

Oxygen bleach is hydrogen peroxide with some sodium and sometimes carbon added to it to form a compound that releases the hydrogen peroxide when added to water. Oxygen leach is a more highly concentrated product than chlorine bleach. Many times, it is found in powdered form, which is then added to water to activate it. Oxygen bleach is known as “color-safe” or “all fabric” bleach, since it does not degrade most fabric or strip most color if used correctly, though you must still test colorfastness before using. It is very stable and can be kept for over a year with no loss of effectiveness. However, it should never be stored in metal or organic containers.

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Oxygen bleach is safe to use on nearly any fabric and to add to laundry loads for extended periods with no damage to clothing. Oxygen bleach turns to water and oxygen when broken down, so it has no negative impact to the environment and is safe for septic systems. It is best if used in the same step as laundry detergent, which makes it even more effective, but combining steps also saves time. It only works well in hot water, but additives can make it effective in warm water.

4 0
4 years ago
The lower the angle of the slope, ________ the acceleration along the ramp, therefore, the speed at the bottom of a slope will b
pogonyaev

Answer:

Lower

Lower

gsintheta (gsinθ)

Explanation:

The sum of forces resolved parallel to the inclined plane is given by;

F - mgsinθ = 0

ma - mgsinθ = 0

ma = mgsinθ

a = gsinθ

Acceleration is proportional to angle of inclination, thus the lower the angle of the slope, lower the acceleration along the ramp.

therefore, the speed at the bottom of a slope will be lower, (velocity is directly proportional to acceleration) and, consequently, the control will be better.

The acceleration along the ramp, is gsintheta (gsinθ)

3 0
4 years ago
Kepler deduced this law of motion from observations of Mars. What information confirms his conclusion that the orbit of Mars is
Leno4ka [110]

Kepler noticed an imaginary line drawn from a planet to the Sun and this line swept out an equal area of space in equal times, If we then draw a triangle out from the Sun to a planet’s position at one point in time, it is notice that the area doesn't change even after the planet has left the original position say like after 2 to 3days or 2hours. So to have same area of triangle means that the the planet move faster when that are closer to the sun and slowly when they are far from the sun.

This led to Kepler's law of orbital motion.

First Law: Planetary orbits are elliptical with the sun at a focus.

Second Law: The radius vector from the sun to a planet sweeps equal areas in equal times.

Third Law: The ratio of the square of the period of revolution and the cube of the ellipse semi-major axis is the same for all planets.

It is this Kepler's law that makes Newton to come up with his own laws on how planet moves the way they do.

6 0
4 years ago
A cheetah can run at a maximum speed 103 km/h and a gazelle can run at a maximum speed of 76.5 km/h. If both animals are running
Katena32 [7]

Answer:

1

 t_a  =  13.49 \  s

2

 The distance is   D = 55.2 \  m    

Explanation:

From the question we are told that

   The maximum speed of the cheetah is  v =  103 \  km/h =  28.61 \  m/s

    The maximum of  gazelle is  u =  76.5 \  km/h =  21.25 \  m/s

     The distance ahead is d =  99.3 \  m

Let  t_a denote the time which the cheetah catches the gazelle

Gnerally the equation representing the distance the cheetah needs to move in order to catch the gazelle is

           v* t_a = d +  u* t_a

=>          28.61 t_a = 99.3 +  21.25t_a

=>          7.36 t_a = 99.3

=>         t_a  =  13.49 \  s

Now at t =  7.5 s  

             7.5 v = D+  7.5u

=>          28.61 * 7.5  = D +  21.25* 7.5

=>          7.36 *  7.5 =D

=>         D = 55.2 \  m        

Hence the for the gazelle to escape the cheetah it must be 55.2 m

5 0
3 years ago
A 6 m long, uniform ladder leans against a frictionless wall and makes an angle of 74.3 ◦ with the floor. The ladder has a mass
olganol [36]

Answer: µ=0.205

Explanation:

The horizontal forces acting on the ladder are the friction(f) at the floor and the normal force (Fw) at the wall. For horizontal equilibrium,

f=Fw

The sum of the moments about the base of the ladder Is 0

ΣM = 0 = Fw*L*sin74.3º - (25.8kg*(L/2) + 67.08kg*0.82L)*cos74.3º*9.8m/s²

Note that it doesn't matter WHAT the length of the ladder is -- it cancels.

Solve this for Fw.

0= 0.9637FwL - (67.91L)2.652

Fw=180.1/0.9637

Fw=186.87N

f=186.81N

Since Fw=f

We know Fw, so we know f.

But f = µ*Fn

where Fn is the normal force at the floor --

Fn = (25.8 + 67.08)kg * 9.8m/s² =

910.22N

so

µ = f / Fn

186.81/910.22

µ= 0.205

4 0
3 years ago
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