Answer: 529.9 Hz
Explanation:
Here we need to use the Doppler equation, so we have:
f' = f*(v + v0)/(v - vs)
Here, f is the frequency = 500Hz
v is the velocity of the wave, = 334m/s
v0 is the velocity of the observer = 20m/s
vs is the velocity of the source = 0m/s
Then we have:
f' = 500Hz*(334m/s + 20m/s)/(334m/s) = 529.9 Hz
Answer:
d. 37 °C
Explanation:
= mass of lump of metal = 250 g
= specific heat of lump of metal = 0.25 cal/g°C
= Initial temperature of lump of metal = 70 °C
= mass of water = 75 g
= specific heat of water = 1 cal/g°C
= Initial temperature of water = 20 °C
= mass of calorimeter = 500 g
= specific heat of calorimeter = 0.10 cal/g°C
= Initial temperature of calorimeter = 20 °C
= Final equilibrium temperature
Using conservation of heat
Heat lost by lump of metal = heat gained by water + heat gained by calorimeter

Answer: Examples of conductors include metals, aqueous solutions of salts (i.e., ionic compounds dissolved in water), graphite, and the human body. Examples of insulators include plastics, Styrofoam, paper, rubber, glass and dry air.
Your answer would be A. Halogens
Answer:
t=2.10 s
u= 47.40 m/s
Explanation:
given that
h= 21.8 m
x= 101 m
g=9.8 m/s²
Lets take horizontal speed of ball = u m/s
The vertical speed of the car at initial condition is zero ( v= 0).
We know that

v= 0 m/s

now by putting the values
21.8 = 1/2 x 9.8 x t²
t=2.10 s
This is time when ball was in motion.
Now in horizontal direction
x = u .t
101 = u x 2.1
u= 47.40 m/s