Question

a 10 kg mass is lifted to 3 m. what is its weight? what is its potential energy? how much work is being done?
a weight = 30 newtons, pe = 30 joules, work = 294 joules
b weight = 10 kg, pe = 10 joules, work = 30 joules
c weight = 98 newtons, pe = 294 joules, work = 294 joules
d weight = 98 newtons, pe = 294 joules, work = 30 joules

Explanation:

Step1: Calculate weight

Weight \(W = mg\), where \(m = 10\ kg\) and \(g=9.8\ m/s^{2}\). So \(W=10\times9.8 = 98\ N\).

Step2: Calculate potential energy

Gravitational - potential energy \(PE = mgh\), with \(m = 10\ kg\), \(g = 9.8\ m/s^{2}\), and \(h = 3\ m\). Then \(PE=10\times9.8\times3=294\ J\).

Step3: Calculate work done

The work done in lifting the mass is equal to the change in its potential energy. So \(W_{done}=PE = 294\ J\).

Answer:

C. weight = 98 newtons, PE = 294 joules, Work = 294 joules