Question

an object with a total of 120000 j of gravitational potential energy on a 75 m tall cliff would have a mass of (ignore sig figs)
163 kg
163 g
16.3 kg
1600 kg
1630 n
the kinetic energy of a 5.0 kg object moving at a speed of 12 m/s would be:
720 n
720 j
360 n
360 j
0 j

Explanation:

First Question

Step1: Recall the formula for gravitational potential energy

The formula for gravitational potential energy is \(U = mgh\), where \(U\) is the gravitational potential energy, \(m\) is the mass, \(g = 9.8\space m/s^{2}\) (acceleration due to gravity), and \(h\) is the height. We need to solve for \(m\), so \(m=\frac{U}{gh}\).

Step2: Substitute the given values

Given \(U = 120000\space J\), \(h = 75\space m\), and \(g=9.8\space m/s^{2}\). Then \(m=\frac{120000}{9.8\times75}\).

$$m=\frac{120000}{735}\approx163\space kg$$

Second Question

Step1: Recall the formula for kinetic energy

The formula for kinetic energy is \(K=\frac{1}{2}mv^{2}\), where \(m\) is the mass and \(v\) is the velocity.

Step2: Substitute the given values

Given \(m = 5.0\space kg\) and \(v = 12\space m/s\). Then \(K=\frac{1}{2}\times5.0\times(12)^{2}\).

$$K = 2.5\times144=360\space J$$

Answer:

First Question: \(163\space kg\)
Second Question: \(360\space J\)