Answer: V = 15 m/s
Explanation:
As stationary speed gun emits a microwave beam at 2.10*10^10Hz. It reflects off a car and returns 1030 Hz higher. The observed frequency the car will be experiencing will be addition of the two frequency. That is,
F = 2.1 × 10^10 + 1030 = 2.100000103×10^10Hz
Using doppler effect formula
F = C/ ( C - V) × f
Where
F = observed frequency
f = source frequency
C = speed of light = 3×10^8
V = speed of the car
Substitute all the parameters into the formula
2.100000103×10^10 = 3×10^8/(3×10^8 -V) × 2.1×10^10
2.100000103×10^10/2.1×10^10 = 3×108/(3×10^8 - V)
1.000000049 = 3×10^8/(3×10^8 - V)
Cross multiply
300000014.7 - 1.000000049V = 3×10^8
Collect the like terms
1.000000049V = 14.71429
Make V the subject of formula
V = 14.71429/1.000000049
V = 14.7 m/s
The speed of the car is 15 m/s approximately.
When light is reflected by a mirror, the angle of incidence is always <span>A. equal to the angle of reflection. We know this by the Law of Reflection.</span>
Answer:
just before landing the ground
Explanation:
Let the velocity of projection is u and the angle of projection is 30°.
Let T is the time of flight and R is the horizontal distance traveled. As there is no force acting in horizontal direction, so the horizontal velocity remains constant. Let the particle hits the ground with velocity v.
initial horizontal component of velocity, ux = u Cos 30
initial vertical component of velocity, uy = u Sin 30
Time of flight is given by
Final horizontal component of velocity, vx = ux = u Cos 30
Let vy is teh final vertical component of velocity.
Use first equation of motion
vy = uy - gT
vy = - u Sin 30
The magnitude of final velocity is given by
v = u
Thus, the velocity is same as it just reaches the ground.
Answer:
50280 meters
Explanation:
33.52 meters/seconds is 2011.2 meters/minutes (multiply by 60)
2011.2 meters/m * 25 minutes = answer
Answer:
<em>58,800Joules</em>
Explanation:
The energy lost is equal to the workdone by the car as it skids.
Workdone = Force * Distance
Given
Force = 8000N
Get the distance using the equation of motion
v² = u² - 2gS
0² = 12² - 2(9.8)S
-12² = - 2(9.8)S
-144 = -19.6S
S = 144/19.6
S = 7.35m
Calculate the required energy
Workdone = 8000 * 7.35
Workdone = 58,800Joules
<em>Hence the energy lost due to friction is 58,800Joules</em>
