Answer:
P=9.58 W
Explanation:
According to Newton's second law, and assuming friction force as zero:
[tex]F_m=m.a\\F_m=0.875kg*a[/tex]
The acceleration is given by:
[tex]a=\frac{\Delta v}{t}\\a=\frac{0.685m/s}{21.5*10^{-3}s}\\\\a=31.9m/s^2[/tex]
So the force exerted by the motor is:
[tex]F_m=0.875kg*31.9m/s^2\\F_m=27.9N[/tex]
The work done by the motor is given by:
[tex]W_m=F_m*d\\\\d=\frac{1}{2}*a*t^2\\d=\frac{1}{2}*31.9m/s^2*(21.5*10^{-3}s)^2\\\\d=7.37*10^{-3}m[/tex]
[tex]W_m=27.9N*7.37*10^{-3}m\\W_m=0.206J[/tex]
And finally, the power is given by:
[tex]P=\frac{W_m}{t}\\P=\frac{0.206J}{21.5*10^{-3}s}\\\\P=9.58W[/tex]
