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fiasKO [112]
3 years ago
5

A person shooting at a target from a distance of 450 metres finds that the sound of the bullet hitting the target comes 1 / 2 se

conds after he fired. A person equidistant from the target and shooting point hears the bullet hit 3 seconds after he heard the gun. The speed of sound is ___.
Physics
1 answer:
White raven [17]3 years ago
3 0

Answer:

1350 m/s

Explanation:

Speed of bullet

Distance traveled by the bullet = 450 m

Distance traveled by sound = 450 m

Using S= V × t

==> t= S/V

So, time for bullet t1=450/vb

time for sound t2=450/vs

Because it takes 1/2 sec from firing to hearing of sound by the shooter

==>  t1+t2= 1/2 sec

==> 450/vb+450/vs=0.5sec  ---- (1)

Now a person at distance 'x' each from gun and target takes 3 sec to hear sound from firing to hitting the target.

Fire sound duration

Distance =x m

Speed of sound = V

time =T1

==> T1 = x/vs

Bullet hitting + target sound  duration

During this duration bullet travels a distance of 450 m and sound of hitting travels a distance 'x'

time taken by sound = 450/vb

time taken by sound to travel distance 'x'= x/vs

so let T2= 450/vb + x/vs

But all this happens in 3 sec i-e T = 3 sec

and because firing occurs before hitting the target so he hears strike sound in time T = T2-T1= 450/vb + x/vs -x/vs

But T= 3sec

==> 3= 450/vb

==> vb= 1350 m/s

From eq 1 and 2

again using same relation as above, i-e within 3 seconds he watches bullet traveling a distance of 450 m and hearing sound

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6 0
3 years ago
A 0.10 kg baseball travelling at 40 m s−1 hits straight back to the pitcher at 55 m s−1. The contact time is 0.01 seconds. What
Ilia_Sergeevich [38]

Answer:

1.5 kgms⁻¹

Explanation:

Momentum can be defined as "<em>mass in motion</em>."  

The amount of momentum that an object has is dependent upon two factors

  • mass of the moving object  
  • speed of motiom 

when there is a change in the velocity , it creates a change in momentum also

when we consider that we can mathematically show this,In terms of an equation,

Change in momentum    (ΔΡ) = m(Δv)

where (Δv) - change in velocity

<em>(Δv) = final velocity - initial velocity</em>

Change in momentum (ΔΡ) = m(Δv)

                                             = 0.1×([55-40])

                                             = 1.5 kgms⁻¹

     

7 0
3 years ago
A powerful motorcycle can produce an acceleration of 3.50 m/s2 while traveling at 90.0 km/h. At that speed the forces resisting
IrinaK [193]

Answer:1265 N

Explanation:

Given

acceleration of motorcycle \left ( a\right )=3.5 m/s^2

Velocity \left ( v\right )=90 km/h\approx 25m/s

Air friction and Friction\left ( f\right )=425 N

mass of the motorcycle with rider\left ( m\right )=240 Kg

Applying Forces on motorcycle

F_{engine}-f=ma

F_{engine}=f+ma

F_{engine}=425+240\left ( 3.5\right )

F_{engine}=425+840=1265 N

5 0
3 years ago
The cornea behaves as a thin lens of focal lengthapproximately 1.80 {\rm cm}, although this varies a bit. The material of whichi
Keith_Richards [23]

Answer:

Explanation:

  a )

from lens makers formula

\frac{1}{f} =(\mu-1)(\frac{1}{r_1} -\frac{1}{r_2})

f is focal length , r₁ is radius of curvature of one face and r₂ is radius of curvature of second face

putting the values

\frac{1}{1.8} =(1.38-1)(\frac{1}{.5} -\frac{1}{r_2})

1.462 = 2 - 1 / r₂

1 / r₂ = .538

r₂ = 1.86 cm .

= 18.6 mm .

b )

object distance u = 25 cm

focal length of convex lens  f  = 1.8 cm

image distance  v   = ?

lens formula

\frac{1}{v} - \frac{1}{u} = \frac{1}{f}

\frac{1}{v} - \frac{1}{-25} = \frac{1}{1.8}

\frac{1}{v} = \frac{1}{1.8} -\frac{1}{25}

.5555 - .04

= .515

v = 1.94 cm

c )

magnification = v / u

= 1.94 / 25

= .0776

size of image = .0776 x size of object

= .0776 x 10 mm

= .776 mm

It will be a real image and it will be inverted.

 

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3 years ago
A solid element that is malleable' a good conductor of electricity, and reacts with oxygen is classified as a
Finger [1]
1) metal
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Metals are very good conductors of electricity and heat. They are also very hard to touch. Noble gases and non metals are the exact opposite in physical and chemical properties. Metals readily react with oxygen.
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