Respuesta :
Answer
Given
Mass of the elevator , m = 700 kg
Initial velocity of elevator is , vi = 0 m/s
Time taken , t = 4.50 s
Speed of the elevator is, v = 1.75 m/s
Acceleration of elevator is , [tex]a = \dfrac{v}{t}[/tex]
                     [tex]a = \dfrac{1.75}{4.5}[/tex]
                         a = 0.389 m/s²
a) Net force on elevator is
    T = mg + ma = m (g +a)
    T = 700 kg( 9.8+0.389)
     T = 7132.3 N
Average velocity is , v' = 1.75 /2 = 0.875 m/s
Average power , P = T v' = 7132.3 × 0.875 m/s
              P = 6240.76 W
b) Power input from motor is
     P = F x v = mg x v
       = 700 x 9.8 * 1.75 m/s
    P = 12005 W
Answer:
(a). The average power of the elevator motor during this period is 6235.25 W.
(b). The power input from motor is [tex]1.2\times10^{4}\ W[/tex]
Explanation:
Given that,
Mass of elevator =700 kg
Initial velocity = 1.75 m/s
Time = 4.50 s
We need to calculate the acceleration of the elevator
Using formula of acceleration
[tex]a = \dfrac{v}{a}[/tex]
Put the value into the formula
[tex]a=\dfrac{1.75}{4.50}[/tex]
[tex]a=0.38\ m/s^2[/tex]
We need to calculate net force on elevator
Using formula of net force
[tex]T=mg+ma[/tex]
[tex]T=m(g-a)[/tex]
Put the value into the formula
[tex]T=700(9.8+0.38)[/tex]
[tex]T=7126\ N[/tex]
We need to calculate the average velocity
Using formula of average velocity
[tex]v'=\dfrac{v_{f}-v_{i}}{2}[/tex]
Put the value into the formula
[tex]v'=\dfrac{1.75-0}{2}[/tex]
[tex]v'=0.875\ m/s[/tex]
(a). We need to calculate the average power of the elevator motor during this period
Using formula of power
[tex]P=T\times v'[/tex]
Put the value into the formula
[tex]P=7126\times0.875[/tex]
[tex]P=6235.25\ W[/tex]
(b). We need to calculate power input from motor
Using formula of power
[tex]P=F\times v[/tex]
[tex]P=mg\times v[/tex]
Put the value into the formula
[tex]P=700\times9.8\times1.75[/tex]
[tex]P=1.2\times10^{4}\ W[/tex]
Hence, (a). The average power of the elevator motor during this period is 6235.25 W.
(b). The power input from motor is [tex]1.2\times10^{4}\ W[/tex]
