2.1

What quantity describes how quickly you change how fast you're traveling, or how quickly you change your direction

acceleration

Why is it that an object can accelerate while traveling at constant speed, but not at constant velocity?

direction can change while traveling at a constant speed, but direction is constant if velocity is constant

What two controls on a car cause a change in speed? What control(s) causes a change in velocity but not a change in speed?

The gas pedal and brake change the speed. The steering wheel changes the velocity but not the speed.

Light travels in a straight line at a constant speed of 300,000 km/s. What is the light ́s acceleration?

0 km/s

What is the difference between instantaneous speed and average speed? Does the speedometer of a car read instantaneous speed or average speed?

Instantaneous is speed at a given moment and average is measured over a duration of time. Speedometers measure instantaneous.

Which has more acceleration when moving in a straight line- a car increasing its speed from 50 to 60 km/hr, or a bicycle that goes from zero to 10 km/hr in the same time?

Both have equal changes in speed over equal time intervals which means their accelerations are also equal.

What do we mean when we say that motion is relative? What is everyday motion usually relative to?

Motion is always measured in reference to another object. Everyday motion is relative to Earth's surface.

If the speedometer of a car reads a constant speed of 40 km/h, can you say that the car has a constant velocity? Why or why not?

No, the car may be changing directions while traveling at a constant speed.

Speed is the rate at which what happens? Acceleration is the rate at which what happens?

Speed is the rate at which distance covered changes. Acceleration is the rate at which velocity changes.

What is the difference between speed and velocity?

Velocity describes both speed and direction and speed does not describe direction.