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4 years ago

Robby skateboards 0.50 blocks to his friend's house in 1.2 minutes. What is his speed?

Physics

2 answers:

KonstantinChe [14]4 years ago

5 0

.42 the direction of his friends house

bogdanovich [222]4 years ago

3 0

<span>velocity = distance / time
v=0.50/1.2
v=</span><span>0.42 blocks/min, in the direction of his friend's house
hope this helps</span>

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4 years ago

Radar uses radio waves of a wavelength of 2.4 ${\rm m}$ . The time interval for one radiation pulse is 100 times larger than t

blondinia [14]

Answer:

120 m

Explanation:

Given:

wavelength 'λ' = 2.4m

pulse width 'τ'= 100T ('T' is the time of one oscillation)

The below inequality express the range of distances to an object that radar can detect

τc/2 < x < Tc/2 ---->eq(1)

Where, τc/2 is the shortest distance

First we'll calculate Frequency 'f' in order to determine time of one oscillation 'T'

f = c/λ (c= speed of light i.e 3 x $10^{8}$ m/s)

f= 3 x $10^{8}$ / 2.4

f=1.25 x $10^{8}$ hz.

As, T= 1/f

time of one oscillation T= 1/1.25 x $10^{8}$

T= 8 x $10^{-9}$ s

It was given that pulse width 'τ'= 100T

τ= 100 x 8 x $10^{-9}$ => 800 x $10^{-9}$ s

From eq(1), we can conclude that the shortest distance to an object that this radar can detect:

$x_{min}$ = τc/2 => (800 x $10^{-9}$ x 3 x $10^{8}$ )/2

$x_{min}$ =120m

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4 years ago

Which evidence did Ottowa scientists collect in researching PCB concentrations in Alaska?

Sergio [31]

PCBs were found in greater concentrations in lakes where more salmon spawned.

7 0

3 years ago

Read 2 more answers

A tennis ball hits with an initial velocity of 25 m/s [10 o above the

Sav [38]

First, calculate the components of its initial velocity v0:

v0x = v0cos10 = 24.6 m/s

v0y = v0sin10 = 4.34 m/s

The ball reaches its peak when vy = 0. Let's calculate the time it takes for vy to become zero:

vy = v0y - gt ---> t = v0y/g = 0.44 s

The horizontal distance it travels in this time is

x = v0xt = (24.6 m/s)(0.44 s)

= 10.8 m

Note that the net is 15 m away. After traveling a horizontal distance of 10.8 m, the height of the ball is

y = -(1/2)gt^2 + v0yt + 2.1

= -(4.9 m/s^2)(0.44 s)^2 + (4.34 m/s)(0.44 s) + 2.1 m

= -0.95 m + 1.9 m + 2.1 m

= 3.05 m

Note that this is the height of the ball at its peak. While the ball is well above the net at its peak, it is well short of its required horizontal distance to clear it. Instead, let's find the time it takes for the tennis ball to travel a horizontal distance of 15 m first:

x = v0xt ----> t = x/v0x = (15 m)/(24.6 m/s) = 0.61 s

Then calculate the height y when t = 0.61 s. If y > 0.9 m (height of the net), then the ball will clear the net.

y = -4.9t^2 + v0yt + 2.1

= -4.9(0.61 s)^2 + (4.34 m/s)(0.61 s) + 2.1 m

= -1.82 m + 2.65 m + 2.1 m

= 2.93 m

Yes, the ball will clear the net by 2.03 m.

3 0

3 years ago

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dmitriy555 [2]

Answer:

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8. 0.5 kg

9. 4 kg

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The equation is F=MA

where F is force in Newtons

M is mass in kg

A is acceleration in m/s^2

for each you substitute in the F and A, and you are finding M. Meaning you divide F by A.

M = F/A

6/3 = 2

6/12 = 0.5

20/5 = 4

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3 years ago

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