Question

1. choose the best answer.

isaiah runs for exercise. he runs 6.2 km in 20 min.
calculate his average speed.
3.2 km/min
1.5 km/min
0.8 km/min
0.3 km/min

1. choose the best answer.

which force must an unbalanced force overcome before an object can move?
sliding friction
kinetic energy
mechanical energy
static friction

Explanation:

Step1: Recall the formula for average speed

The formula for average speed \(v\) is \(v=\frac{d}{t}\), where \(d\) is the distance and \(t\) is the time.

Step2: Substitute the given values into the formula

Given \(d = 6.2\) km and \(t=20\) min. Then \(v=\frac{6.2}{20}\) km/min.

Step3: Calculate the value

\(\frac{6.2}{20}=0.31\approx0.3\) km/min.

Static friction is the force that opposes the start of motion of an object. Sliding friction acts when the object is already in motion. Kinetic energy is the energy of motion and mechanical energy is the sum of potential and kinetic energy. An unbalanced force must overcome static friction for the object to move.

Answer:

0.3 km/min