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photoshop1234 [79]
3 years ago
5

4) Jessica and Martin start riding their bicycles towards each other at 2 pm. At 2 pm, they are 25 miles apart. Jessica rides he

r bike at a constant rate of 15 miles per hour and Martin rides his at a constant rate of 10miles per hour. At 2 pm, a bird starts flying towards Martin. As soon as the bird gets to Martin, it turns back around and flies towards Jessica, and continues going back and forth until Jessica and Martin meet. The bird travels at a constant rate of 45 miles per hour. How far does the bird fly from the time it starts until Jessica and Martin meet? Assume that it takes the bird no time to turn around and fly the other direction.
Physics
1 answer:
Whitepunk [10]3 years ago
8 0

Answer:

45 mi

Explanation:

Distance between Jassica and Martin = 25 mi

Relative velocity of them = 15 + 10 = 25 mi/h ( they are going towards each other. )

Time taken by them to meet each other

= 25 / relative velocity

=25 / 25 = 1 hour.

Speed of bird = 45 mi / hr

Distance traveled by bird during this one hour

= 45 mi

A distance of 45 mi , the bird will  fly from the time it starts until Jessica and Martin meet .

You might be interested in
A quantity of a gas has an absolute pressure of 400 kPa and an absolute temperature of 110 degrees kelvin. When the temperature
shepuryov [24]

You can make sure there's no change in volume by keeping
your gas in a sealed jar with no leaks.  Then you can play with
the temperature and the pressure all you want, and you'll know
that the volume is constant.

For 'ideal' gases,

       (pressure) times (volume) is proportional to (temperature).

And if volume is constant, then

                 (pressure) is proportional to (temperature) .

So if you increase the temperature from 110K to 235K,
the pressure increases to  (235/110)  of where it started.

     (400 kPa) x (235/110)  =  854.55 kPa. (rounded)

Obviously, choice-b is the right one, but
I don't know where the .46 came from.
 
4 0
3 years ago
1. A 2.5 kg led projector is launched as a projectile off a tall building. At one point, as it
spin [16.1K]

Answer:

Explanation:

I got everything but i. Don't know why but it's eluding me. So let's do everything but that.

a. PE = mgh so

   PE = (2.5)(98)(14) and

   PE = 340 J

b. KE=\frac{1}{2}mv^2 so

   KE=\frac{1}{2}(2.5)(14)^2 and

   KE = 250 J

c. TE = KE + PE so

   TE = 340 + 250 and

   TE = 590 J

d. PE at 8.7 m:

   PE = (2.5)(9.8)(8.7) and

   PE = 210 J

e. The KE at the same height:

   TE = KE + PE and

   590 = KE + 210 so

   KE = 380 J

f. The velocity at that height:

   380=\frac{1}{2}(2.5)v^2 and

   v=\sqrt{\frac{2(380)}{2.5} } so

   v = 17 m/s

g. The velocity at a height of 11.6 m (these get a bit more involed as we move forward!). First we need to find the PE at that height and then use it in the TE equation to solve for KE, then use the value for KE in the KE equation to solve for velocity:

   590 = KE + PE and

   PE = (2.5)(9.8)(11.6) so

   PE = 280 then

   590 = KE + 280 so

   KE = 310 then

   310=\frac{1}{2}(2.5)v^2 and

   v=\sqrt{\frac{2(310)}{2.5} } so

   v = 16 m/s

h. This one is a one-dimensional problem not using the TE. This one uses parabolic motion equations. We know that the initial velocity of this object was 0 since it started from the launcher. That allows us to find the time at which the object was at a velocity of 26 m/s. Let's do that first:

   v=v_0+at and

   26 = 0 + 9.8t and

   26 = 9.8t so the time at 26 m/s is

   t = 2.7 seconds. Now we use that in the equation for displacement:

   Δx = v_0t+\frac{1}{2}at^2 and filling in the time the object was at 26 m/s:

   Δx = 0t + \frac{1}{2}(-9.8)2.7)^2 so

   Δx = 36 m

i. ??? In order to find the velocity at which the object hits the ground we would need to know the initial height so we could find the time it takes to hit the ground, and then from there, sub all that in to find final velocity. In my estimations, we have 2 unknowns and I can't seem to see my way around that connundrum.

4 0
2 years ago
In an orbiting space shuttle, you are handed two identical boxes, one filled with sand and the other filled with feathers. How c
Aleks04 [339]

Explanation:

Simply, shake the boxes. The box that is difficult to shake will be the sand and the box that will be easier will be the feathers.

3 0
3 years ago
Most geologists believe that the dinosaurs became extinct 65 million years ago when a large comet or asteroid struck the earth,
Alex17521 [72]

Answer:

A) 1.67 x 10 ⁻⁶ m/s

B)5.59 x 10^-^9 %

Explanation:

A)

Given:

d = 5.0 km,

mₐ = 2.5 x 10^1^4 kg

u₁ = 4.0 x 10⁴ m/s

m_n = 5.98 x 10 ²⁴ kg

Solve using kinetic conserved energy

mₐ x u₁ + m_n  x u₂ = uₓ x (mₐ + m_n )

(2.5 x 10^1^4) (4.0 x 10⁴ )+ (5.98 x 10 ²⁴ )(0) = uₓ x (2.5 x 10^1^4 + 5.98 x 10 ²⁴ )

uₓ = ( 2.5 x 10^1^4 x 4.0 x 10⁴ ) / (2.5 x 10^1^4 + 5.98 x 10 ²⁴ )    

uₓ = 1.67 x 10 ⁻⁶ m/s

B) Assuming earth radius as a R = 1.5 x 10 ¹¹ m

t = 365 days  x 24 hr / 1 day x 60 minute / 1 hr x 60s / 1 minute = 31536000 s

t = 31536000 s

D = 2 π R = 2 π( 1.5 x 10 ¹¹ )

D = 9.4247 x 10 ¹¹ m

u₂  = D / t  = 9.4247 x 10 ¹¹  / 31536000

u₂ =  29885.775 m/s

% = (  1.67 x 10 ⁻⁶ m/s ) / (29885.775 m/s) x 100

% = 5.59 x 10^-^9 %

5 0
3 years ago
Will mark as BRAINLIEST.......
lubasha [3.4K]

Answer:

We have the position vector given in terms of time t. r(t) = t^3*i + t^2*j

To find the velocity vector we have to differentiate r(t) with respect to time.

r'(t) = 3t^2*i + 2t*j

The vector representing acceleration is the derivative of the position vector

r''(t) = 6t*i + 2*j

When time t = 2.

The velocity vector is 3*2^2*i + 2*2*j

=> 12*i + 4*j

The speed is the absolute value of the velocity vector or sqrt(12^2 + 4^2) = sqrt (144 + 16) = sqrt 160

The acceleration vector is 6*2*i + 2*j

=> 12*i + 2*j

The required acceleration at t=2 is 12*i + 2*j and the speed is sqrt 160.

Explanation:

Can I have thx and brainliest?

6 0
2 years ago
Read 2 more answers
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