Question

7 formula 1 point what is the power rating of a motor that is able to raise a 1,422 kg elevator 2 meters in 17.8 seconds? report your answer to 1 decimal place. your permitted error is ±0.1 watts. do not put units into the answer field. answer 8 formula 1 point calculate the potential energy of a 62 kg person sitting on top of a 8 m tree. report your answer to 1 decimal place. your permitted error is ±0.1 j. do not put units into the answer field. answer

Explanation:

Step1: Calculate work done for motor problem

Work \(W = mgh\), where \(m = 1422\) kg, \(g= 9.8\) m/s², \(h = 2\) m. So \(W=1422\times9.8\times2\).

$$W = 1422\times9.8\times2=1422\times19.6 = 27871.2$$

J

Step2: Calculate power of the motor

Power \(P=\frac{W}{t}\), \(W = 27871.2\) J, \(t = 17.8\) s. So \(P=\frac{27871.2}{17.8}\)

$$P=\frac{27871.2}{17.8}\approx1565.8$$

W

Step3: Calculate potential - energy for person problem

Potential energy \(U = mgh\), \(m = 62\) kg, \(g = 9.8\) m/s², \(h = 8\) m. So \(U=62\times9.8\times8\)

$$U=62\times9.8\times8=62\times78.4 = 4860.8$$

J

Answer:

1565.8
4860.8