HW 2.3 Speed, Velocity, and Acceleration

Which of the following quantities has units of velocity? (There could be more than one correct choice.)

• 40 km southwest

• -120 m/s

• 9.8 m/s² downward

• 9.8 m/s downward

You drive 6.0 km at 50 km/h and then another 6.0 km at 90 km/h. Your average speed over the 12 km drive will be ___.

• greater than 70 km/h

• equal to 70 km/h

• less than 70 km/h

• exactly 38 km/h

• It cannot be determined from the information given because we must also know directions traveled.

What must be your average speed in order to travel 350 km in 5.15 h?

• 66.0 km/h

• 67.0 km/h

• 68.0 km/h

• 69.0 km/h

If you run a complete loop around an outdoor track of length 400 m in 100 s, what is your average velocity in m/s? (Only write the number with no decimals.)

A polar bear starts at the North Pole. It travels 1.0 km south, then 1.0 km east, and then 1.0 km north to return to its starting point. This trip takes 45 min. What was the bear's average velocity?

• 0.00 km/h

• 0.067 km/h

• 4.0 km/h

• 5.3 km/h

A motorist travels for 3.0 h at 80 km/h and 2.0 h at 100 km/h. What is her average speed for the trip?

• 85 km/h

• 88 km/h

• 90 km/h

• 92 km/h

If, in the figure, you start from the Bakery, travel to the Cafe, and then to the Art Gallery in 2.00 hours, what is your (a) average speed and (b) average velocity?

• (a) 5.25 km/h, (b) 1.25 km/h south

• (a) 5.25 km/h south, (b) 1.25 km/h

• (a) 1.25 km/h south, (b) 5.25 km/h

• (a) 1.25 km/h, (b) 5.25 km/h south

A car is traveling north at 17.7 m/s. After 12 s its velocity is 14.1 m/s in the same direction. What is the magnitude and direction of the car's average acceleration.

• 0.30 m/s², south

• 2.7 m/s², south

• 0.30 m/s², north

• 2.7 m/s², north

A car travels at 15 m/s for 10 s. It then speeds up with a constant acceleration of 2.0 m/s² for 15 s. At the end of this, what is its velocity?

• 15 m/s

• 30 m/s

• 45 m/s

• 375 m/s

A cart with an initial velocity of 5.0 m/s to the right experiences a constant acceleration of 2.0 m/s² to the right. What is the cart's displacement during the first 6.0 s of this motion?

• 10 m, right

• 55 m, right

• 66 m, right

• 88 m, right