BEST PRACTICE Relative Velocity

An airplane flies at 200.0 km/h relative to the air. What is the velocity

of the plane (in km/h) relative to the ground if it flies with a 50.0-km/h tailwind? Express the answer as a whole number. No need to write the units.

An airplane flies at 200.0 km/h relative to the air. What is the velocity

of the plane (in km/h) relative to the ground if it flies with a 50.0-km/h headwind?

• 250 km/h

• 150 km/h

• 200 km/h

• 50 km/h

LaToya is rowing on a boat from dock A to dock B and back. The distance between the two docks is 1500 m. The river has a current of 2.0 m/s moving from dock A to dock B as shown. If LaToya’s rowing speed in still water is 4.0 m/s, how much time will it take her to row from dock A to dock B?

• 250 s

• 750 s

• 375 s

• 500 s

LaToya is rowing on a boat from dock A to dock B and back. The distance between the two docks is 1500 m. The river has a current of 2.0 m/s moving from dock A to dock B as shown. If LaToya’s rowing speed in still water is 4.0 m/s, how much time will it take her to row from dock B to dock A?

• 250 s

• 750 s

• 375 s

• 500 s

Odina and LaToya are sitting by a river and decide to have a race. Odina will run down the shore to from dock A to dock B and back. LaToya will row on a boat from dock A to dock B and back. The distance between the two docks is 1500 m. The river has a current of 2 m/s moving from dock A to dock B as shown. If Odina and LaToya have the same speed of 4 m/s, who will win the race and by how much time will the winner be ahead of the other? Assume they both turn instantaneously.

• Odina will win and she'll be ahead of LaToya by 250 s.

• LaToya will win and she'll be ahead of Odina by 250 s.

• Odina will win and she'll be ahead of LaToya by 500 s.

• LaToya will win and she'll be ahead of Odina by 125 s.

You row a boat, such as the one in the figure, perpendicular to the shore of a river that flows at 3.0 m/s in the direction shown. The velocity of your boat is 4.0 m/s relative to the water. What is the magnitude of the velocity (in m/s) of your boat relative to the shore? Express the answer as a whole number. No need to write the units.

A weather station releases a balloon to measure cloud conditions that rises at a constant 15 m/s relative to the air, but there is also a wind blowing at 6.5 m/s toward the west. What is the magnitude of the velocity of the balloon (in m/s) realtive to an observer on the ground?

• 16 m/s

• 267 m/s

• 14 m/s

• 183 m/s

You are riding in a bus moving slowly through heavy traffic at 2.0 m/s. You hurry to the front of the bus at 4.0 m/s relative to the bus. What is your speed (in m/s) relative to the street? Express the answer in 1 decimal place. No need to write the units.

You row a boat, such as the one in the figure, perpendicular to the shore of a river that flows at 3.0 m/s in the direction shown. The velocity of your boat is 4.0 m/s relative to the viewers on the shore. What is the magnitude of the velocity (in m/s) of your boat relative to the river? Express the answer in one decimal place. No need to write the units.

An airplane flies due north at 150 km/h relative to the air. There is a wind blowing to the east. If the plane’s speed relative to the ground is 170 km/h, what is the wind's velocity (km/h) relative to the ground? Express the answer as a whole number. No need to write the units.