Motion

What is the difference between speed and velocity?

• None, they are synonyms.

• Velocity depends on the direction of motion.

• They have different units, km/hr for velocity and m/s for speed.

• Velocity does not depend on the speed.

Acceleration is ...

• a change in velocity.

• speeding up.

• slowing down.

• changing direction.

Which of these would be an example of acceleration?

• a car travelling 70 mph East on the interstate

• a car stopped at a red light

• a car parked in a parking lot facing West

• a car slowing down at a crosswalk

How can you determine speed using a distance vs. time graph?

• find the difference in the x-values for time

• find the difference in the y-values for distance

• look for the straightest line

• calculate the slope of the line

If you determine that the white-board at the front of the room IS in motion, which of the following objects did you likely use as your reference point?

• the clock on the wall

• the lab table at the front of the room

• the windows on the side of the room

• the Sun

If it takes you 10 seconds to walk 20 meters, what is your speed?

• d = s*t = (10)(20) = 200 m/s

• s = d/t = 10/20 = 0.5 m/s

• s = d/t = 20/10 = 2 m/s

• t = d/s = 20/1 = 20 m/s

If a boy is riding a bike at a speed of 2 m/s and it takes him 1 second to come to a stop, what is his acceleration?

• a = Δv/t = (0-2)/1 = -2 m/s²

• a = Δv/t = (2-0)/1 = 2 m/s²

• a = Δv/t = (0-2)/1 = -2² = 4 m/s

• a = Δv/t = 2/1 = 2 m/s²

What does constant speed look like on a distance vs. time graph?

• an upward curve

• a downward curve

• a straight, horizontal line

• a straight line

What does it mean if you see a straight, horizontal line on a distance vs. time graph?

• the object is accelerating

• the object has slowed down

• the object is moving backward

• the object is not moving

You look at a graph of two runners and determine that runner A was moving faster than runner B. What rationale did you likely use?

• runner B's line had a steeper slope

• runner A's line had a steeper slope

• runner A's line was straight

• runner B's line was curved