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12345 [234]
2 years ago
12

The focal length of david's lens is 60 cm. if rebecca stands in front of david at a distance of do and david perceives the posit

ion of rebecca at di, what does do equal if the magnification is -0.40?
Physics
1 answer:
Makovka662 [10]2 years ago
5 0

if rebecca stands in front of david at a distance of do and david perceives the position of rebecca at di, di will be +84 cm

<h3>What is focal length ?</h3>

How strongly light converges or diverges depends on an optical system's focal length, which is the inverse of optical power. A system with a positive focus length is said to converge light, whereas one with a negative focal length is said to diverge light.

focal length = +60 cm

magnification m = -0.40

focal length being positive an magnification negative.

given lens is a convex lens.

for a lens

m = di/do and 1/f = (1/di) - (1/do)di

= -0.4do1/f = (1/-0.4do) - 1/do do

= -210 cmdi = -0.4 * -210

di = +84 cm

To learn more about focal length go to - brainly.com/question/25779311

#SPJ4

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Answer:

the force P required for impending motion is 132.3 N

the largest value of "h" allowed if the cabinet is not to tip over is 0.8 m

Explanation:

Given that:

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coefficient of static friction μ =  0.30

A free flow body diagram illustrating what the question represents is attached in the file below;

The given condition from the question let us realize that ; the casters are locked to prevent the tires from rotating.

Thus; considering the forces along the vertical axis ; we have :

\sum f_y =0

The upward force and the downward force is :

N_A+N_B = mg

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N_A+N_B = 45*9.8

N_A+N_B = 441    ------- equation (1)

Considering the forces on the horizontal axis:

\sum f_x = 0

F_A +F_B  = P

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\mathbf{ F_A \ and \ F_B } are the static friction at center point A and B respectively.

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\mu_s N_A + \mu_s N_B  = P

\mu_s( N_A +  N_B)  = P

replacing our value from equation (1)

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b) Since the horizontal distance between the casters A and B is 480 mm; Then half the distance = 480 mm/2 = 240 mm = 0.24 cm

the largest value of "h" allowed for  the cabinet is not to tip over is calculated by determining the limiting condition  of the unbalanced torque whose effect is canceled by the normal reaction at N_A and it is shifted to N_B:  

Then:

\sum M _B = 0

P*h = mg*0.24

h =\frac{45*9.8*0.24}{132.3}

h = 0.8 m

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hi, this is the answer

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Answer:

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At the highest point, vf= 0.

b) Prior to solve this point, we need to know which is the time when the ball reaches to its highest point.

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v= v₀ -g((v₀/g)-0.7 s) = v₀ - v₀ + g*0.7 s

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