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Vera_Pavlovna [14]

2 years ago

14

Why do slippery fluids such as oil reduce sliding friction

1 answer:

Gwar [14]2 years ago

6 0

fluid friction<span> occurs when an object moves through a liquid or gas. the force needed to overcome </span>fluid friction <span>is usually less then that needed to overcome </span>sliding friction<span>. the </span>fluid<span> keeps the surface from making direct contact and thus </span>reducing friction<span>.</span>

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Why is a noble gas different from other elements

fredd [130]

Because noble gases has full of 8 electron in her external cell......

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2 years ago

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If the diameter of a radar dish is doubled, what happens to its resolving power assuming that all other factors remain unchanged

kirill115 [55]

Answer:

θ’ = θ₀ / 2

we see that the resolution angle is reduced by half

Explanation:

The resolving power of a radar is given by diffraction, for which we will use the Rayleigh criterion for the resolution of two point sources, they are considered resolved if the maximum of diffraction of one coincides with the first minimum of the other.

The first minimum occurs for m = 1, so the diffraction equation of a slit remains

a sin θ = λ

in general, the diffraction patterns occur at very small angles, so

sin θ = θ

θ = λ / a

in the case of radar we have a circular aperture and the equation must be solved in polar coordinates, which introduces a numerical constant.

θ = 1.22 λ /a

In this exercise we are told that the opening changes

a’ = 2 a

we substitute

θ ‘= 1.22 λ / 2a

θ' = (1.22 λ / a) 1/2

θ’ = θ₀ / 2

we see that the resolution angle is reduced by half

8 0

3 years ago

What is energy and object has due to its motion

jolli1 [7]

The energy stored in motion is called kinetic energy.

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3 years ago

A person throws a baseball from height of 7 feet with an initial vertical velocity of 50 feet per second. Use the vertical motio

Gnoma [55]

Answer:

3.25 seconds

Explanation:

It is given that,

A person throws a baseball from height of 7 feet with an initial vertical velocity of 50 feet per second. The equation for his motion is as follows :

$h=-16t^2+vt+s$

Where

s is the height in feet

For the given condition, the equation becomes:

$h=-16t^2+50t+7$

When it hits the ground, h = 0

i.e.

$-16t^2+50t+7=0$

It is a quadratic equation, we find the value of t,

t = 3.25 seconds and t = -0.134 s

Neglecting negative value

Hence, for 3.25 seconds the baseball is in the air before it hits the ground.

6 0

2 years ago

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You're driving down the highway late one night at 21 m/s when a deer steps onto the road 35 m in front of you. Your reaction tim

andreev551 [17]

Speed with which initially car is moving is 21 m/s

Reaction time = 0.50 s

distance traveled in the reaction time d = v t

d = 21 * 0.50 = 10.5 m

deceleration after this time = -10 m/s^2

now the distance traveled by the car after applying bakes

$v_f^2 - v_i^2 = 2a d$

$0 - 21^2 = 2(-10)d$

$d = 22.05 m$

so total distance moved before it stop

d = 22.05 + 10.5 = 32.55 m

so the distance from deer is 35 - 32.55 = 2.45 m

now to find the maximum speed with we can move we will assume that we will just touch the deer when we stop

so our distance after brakes are applied is d = 35 - 10.5 = 24.5 m

again by kinematics

$v_f^2 - v_i^2 = 2 ad$

$0 - v^2 = 2(-10)(24.5)$

$v = 22.1 m/s$

so maximum speed would be 22.1 m/s

5 0

2 years ago