Answer:
3000 kg.m/s
Explanation:
Momentum, p is a product of mass and velocity hence
p=mv where m is mass and v is velocity.
Change in momentum is given by 
where subscripts f and i represent final and initial respectively. Since the lorry finally comes to rest then the final velocity is zero. Substituting the given figures then
Change in momentum= 6000(0-0.5)=-3000 kg.m/s
Answer:
Smaller refractive power
Explanation:
The refractive power of an eye is the extent to which it can converge or diverge the light rays.
Near point is the the closest point for an eye such that when an object is placed at that point the image it forms is sharp and clearly visible to the eye.
A the person ages, the ciliary muscles of the eyes weakens and as a result the lens contracts and the formation of the image takes place behind the retina instead of forming at the retina.
Thus the near point also increases and the refractive power becomes smaller.
Answer:
Explanation:
Assuming uniform spread of sound with no significant reflections or absorption. We know that sound intensity varies 
where r is the distance
Since intensity is given then when at 3 m
Since we have the constant then at 4m
Intensity, 
<span> Rising, warm, moist air masses cool and release precipitation as they rise and then at high altitude, cool
and sink back to the surface as dry air masses after moving north or south of the tropics.
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Answer:
0.69444 m, 0.08152 m, 0.32407 m, 0.03804 m
Explanation:
v = Velocity of sound
f = Frequency
Length of vocal tract is given by
At f = 270 Hz v = 750 m/s
At f = 2300 Hz v = 750 m/s
At f = 270 Hz v = 350 m/s
At f = 2300 Hz v = 350 m/s
