The whistle you use to call has a frequency of 21 kHz, so you do not recognize it also because your threshold of hearing is only 20 kHz. Since you are unable to hear sounds above this value, you request your friend to blow the whistle and move farther away. The frequency will decrease due to Doppler effect.
Vai c fude
..........................................................................
Answer:
Launch velocity of the fleas = 1.80 m/s
Explanation:
Optimal launch angle is the angle that guarantees the maximum horizontal distance covered.
Optimum launch angle = 45°
The horizontal distance covered by a projectile is given as Range
R = (u² sin 2θ)/g
u = initial velocity of the projectile (flea) = ?
R = range = 33 cm = 0.33 m
θ = 45°
2θ = 2 × 45° = 90°
Sin 90° = 1
g = acceleration due to gravity = 9.8 m/s²
R = (u²/g)
u² = Rg = 0.33 × 9.8 = 3.234
u = 1.80 m/s
Hope this helps!!!
B. Thermal energy is the energy that warms the earths surface.
