Question

1. choose the best answer.

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

1. choose the best answer.

which force must an unbalanced force overcome before an object can move?
mechanical energy
kinetic energy
slding friction
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 \(v=\frac{6.2}{20}\).

Step3: Calculate the value

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

For the second question:

Static friction is the force that acts on an object at rest to prevent it from moving. An unbalanced force must overcome static friction for the object to start moving. Mechanical energy is the sum of kinetic and potential energy. Kinetic energy is the energy of motion. Sliding friction acts on an object that is already in motion.

Answer:

1. \(0.3\) km/min
2. static friction