Question

clicker quiz! in the absence of friction, which energy - time diagram is correct? potential energy total energy kinetic energy

Explanation:

Step1: Analyze potential energy

When the object slides down the slope in the absence of friction, its height decreases. According to the formula \(E_p = mgh\) ($h$ is the height), the potential energy \(E_p\) decreases linearly with time.

Step2: Analyze kinetic energy

From the conservation of mechanical energy \(E = E_p+E_k\) (in the absence of non - conservative forces like friction, \(E\) is constant). As \(E_p\) decreases, \(E_k\) increases. Since \(v = v_0+at\) (constant acceleration \(a\) in the absence of friction), \(E_k=\frac{1}{2}mv^{2}\), and \(E_k\) is a quadratic function of time \(t\) at first (when it is on the slope). After reaching the horizontal plane, \(v\) is constant, so \(E_k\) is constant.

Step3: Analyze total energy

In the absence of friction (non - conservative force), the total mechanical energy \(E = E_p + E_k\) is constant.

Answer:

C