Answer:
c) 10.7m/s
Explanation:
From the exercise we know that at 5m the ball is traveling at 4m/s
To calculate its initial velocity we need to solve the following equation:

Since the initial height is 0
Solving for 

Answer:
96%
Explanation:
To find the values of the motor efficiency you use the following formula:

P_o: output power = 864J/0.5min=864J/30s=28.8W
P_i: input power = I*V = (3A)(12V) = 36W
By replacing this values you obtain:

hence, the motor efficiency is about 96%
traslation:
Pentru a găsi valorile eficienței motorului, utilizați următoarea formulă:
P_o: putere de ieșire = 864J / 0.5min = 864J / 30s = 28.8W
P_i: putere de intrare = I * V = (3A) (12V) = 36W
Înlocuind aceste valori obțineți:
prin urmare, eficiența motorului este de aproximativ 96%
Answer:
Explanation:
Y = 5 Sin27( .2x-3t)
= 5 Sin(5.4x - 81 t )
Amplitude = 5 m
Angular frequency ω = 81
frequency = ω / 2π
= 81 / (2 x 3.14 )
=12.89
Wave length λ = 2π / k ,
k = 5.4
λ = 2π / 5.4
= 1.163 m
Phase velocity =ω / k
= 81 / 5.4
15 m / s.
The wave is travelling in + ve x - direction.