Answer
given,
frequency from Police car= 1240 Hz
frequency of sound after return = 1275 Hz
Calculating the speed of the car = ?
Using Doppler's effect formula
Frequency received by the other car
..........(1)
u is the speed of sound = 340 m/s
v is the speed of the car
Frequency of the police car received

now, inserting the value of equation (1)


1.02822(340 - v) = 340 + v
2.02822 v = 340 x 0.028822
2.02822 v = 9.799
v = 4.83 m/s
hence, the speed of the car is equal to v = 4.83 m/s
Answer:
Kinetic energy = (1/2) (mass) (speed²)
First object: (1/2) (2 kg) (2 m/s)² = 4 joules .
Second object: (1/2) (4 kg) (3 m/s)² = 18 joules .
The second object had more kinetic energy than the first one had.
Explanation:
Hot and cold water rising and sinking through other water
is definitely a description of convection.
<span>Carnot cycle efficiency = work done/heat supplied = (Th - Tc)/Th
where, Th is temperature of hot reservoir and Tc is temperature of cold reservoir.
we have given the values as Heat supplied = 1.3 MJ or 1300 KJ, Th = 427 degree C and Tc = 90 degree C.
converting degree Celsius to kelvin temperatures, Th = 427 + 273 = 700 K
Tc = 90 +273 = 363
solving equations, (700 - 363)/700 = work done / 1300
work done = 625.86 KJ i.e. 0.626 MJ work is done .</span>
Answer:
it A i think
hope that helps if not i can change it
Explanation: