24. Wind turbines convert ____________________ energy into electrical energy.
Explanation :22 The mechanical efficiency of any machine is always less than 100 percent.
23. When a pole vaulter flexes the pole, the pole vaulter increases the pole’s elastic potential energy.
24. Wind turbines convert wind energy into electrical energy.
B. linear
C. quadratic
D. direct proportion
Answer:
C. quadratic
Explanation:
Linear graphs are straight lines, and direct proportion graphs are lines that pass through the origin.
Inverse proportion graphs have vertical and horizontal asymptotes passing through the origin.
Quadratic graphs are parabolas.
The graph shown is a parabola, or quadratic.
Answer:
v' = 14.76 m/s
Explanation:
given,
frequency of the one truck = 206 Hz
apparent frequency ,f' = 189 Hz
speed of sound, v = 343 m/s
speed of observer (v_o)and source (v_s) = v'
now, using Doppler's effect
314.69 + 0.9174 v' = 343 - v'
1.9174 v' = 28.30
v' = 14.76 m/s
hence, the speed of the truck is equal to 14.76 m/s