Answer:
a) The car was moving at a speed of 
b) The negative sign of 
denotes that the observer is coming towards the police car which is the source of the sound.
c) 
Explanation:
Given:
- original frequency of the source,
- speed of the source,
- velocity of the obstacle car be,
- speed of sound,
- observed frequency,
<u>Using the equation from the Doppler's effect:</u>
a)
The car was moving at a speed of
b)
The negative sign of denotes that the observer is coming towards the police car which is the source of the sound.
c)
Now when, 
Then, 
Using the Doppler's eq.:
Assuming it is on a horizontal surface:
friction = μR
R = 20g (g is gravity 9.81)
so Friction = 0.085 x 20g
Work done is force x distance
so Work done = 0.085 x 20g x 28
= 466.956 J
Answer:
Part a)
Part b)
Explanation:
Part a)
Torque on the rod is due to two forces
(i) Due to weight of the rod at mid point
(ii) Due to external force applied at the end
Now we have
Part b)
As per Newton's law we know that
now we have
<h3><u>Answer;</u></h3>
Satellite
Differences in ocean-surface height can be measured by<u> Satellite</u>
<h3><u>Explanation;</u></h3>
- The topography of the ocean or the height of the ocean surface relative to a level of no motion provides the information on tides, and the distribution of heat and mass in the Earths's oceans.
- <em><u>The ocean topography is measured using satellites altimeter. Satellites use radar altimeters that are specially made to measure the height of the ocean surface. The satellites measure the height of the ocean surface with an accuracy of 3 cm relative to the center of the earth.</u></em>
- Satellite altimeter combines precise orbit determination with accurate ranging by a microwave altimeter of ocean distance to the satellite.
Density = (mass) / (volume)
Density = (20 g) / (5 cm³)
<em>Density = 4 g/cm³</em> .
The density of the substance is greater than the density of water. A lump of the substance <em>will sink in water</em>, <u>unless</u> the lump is formed into a shape that displaces 20 cm³ of water or more, such as a tiny boat shape.
