Official Relative Velocity Test Review Answer Key

Relative Velocity Example #22 A person is in a motorboat that is capable of a maximum speed of 10 km/hr in still water. She wishes to cross a 2 km wide river to a point directly across from the starting point. If the speed of the water in the river is 6 km/hr; A. How much time is required for crossing, assuming the boat is moving at its maximum speed?

A. 1/4 or .25 hr is required for crossing the river.

Relative Velocity Example #25 Jim is stuck on a tiny island that is being engulfed in flames. Cindy is trying to save him, but she needs to steer the boat so it goes directly across 150m. She needs to get in exactly 60 seconds so that he doesn't burn. The stream pushes 10 m/s to the east. A. Which way should the boat travel?

A. The boat should travel 75.96 degrees W of N.

Relative Velocity Example #21 A boat is traveling across a river with a speed of 4 m/s N when it encounters a river which is flowing east with a speed of 2 m/s. If the river is 120m across; A. What is the boats velocity with the current?

A. The boat's velocity with the current is 4.47 m/s @ 26.57 degrees E of N.

Relative Velocity Example #24 A captain of a boat wants to cross Nort 50m and end up directly across from where she started. The boat can only travel 10 m/s. The river is flowing East with a 5 m/s current. A. In which direction should the captain steer the boat to end up exactly across the river?

A. The captain should steer the boat 30 degrees W of N

Relative Velocity Example #23 A motorboat traveling 4 m/s East encounters a current traveling 3.0 m/s North. A. What is the velocity of the motorboat relevant to the earth?

A. The velocity of the motorboat that is relevant to the earth is 5 m/s @ 36.87 degrees

Relative Velocity Example #26 Two sailors are on a whaleboat that travels at a speed 10.0 km/h. They wish to cross a river 2.0 km wide in the quickest time. The speed of the river is 9.0 kms/hr North to the shore. A. What direction should they point the bow?

A. They should point the bow east

Relative Velocity Example #25 Jim is stuck on a tiny island that is being engulfed in flames. Cindy is trying to save him, but she needs to steer the boat so it goes directly across 150m. She needs to get in exactly 60 seconds so that he doesn't burn. The stream pushes 10 m/s to the east. B. And how fast does Cindy's boat need to go in the water?

B. Cindy's boat need to go 10.3 m/s in the water

Relative Velocity Example #23 A motorboat traveling 4 m/s East encounters a current traveling 3.0 m/s North. B. If the width of the river is 80 meters wide, how much time does it take the boat to travel from shore to shore?

B. It take the boat 20 seconds to travel from shore to shore.

Relative Velocity Example #24 A captain of a boat wants to cross Nort 50m and end up directly across from where she started. The boat can only travel 10 m/s. The river is flowing East with a 5 m/s current. B. How long will it take to cross?

B. It will take 5.77 seconds to cross the river.

Relative Velocity Example #21 A boat is traveling across a river with a speed of 4 m/s N when it encounters a river which is flowing east with a speed of 2 m/s. If the river is 120m across; B. How long will it take to cross?

B. It would take 30.02 seconds to cross.

Relative Velocity Example #22 A person is in a motorboat that is capable of a maximum speed of 10 km/hr in still water. She wishes to cross a 2 km wide river to a point directly across from the starting point. If the speed of the water in the river is 6 km/hr; B. What will the orientation of the boat as it moved across the river? Will it be straight, or angled in a certain direction?

B. The orientation of the boat will be angled to the left as it moves across the river.

Relative Velocity Example #26 Two sailors are on a whaleboat that travels at a speed 10.0 km/h. They wish to cross a river 2.0 km wide in the quickest time. The speed of the river is 9.0 kms/hr North to the shore. B. Find the velocity that the boat moves relative to the ground.

B. The velocity in which the boat moves at is 13.45 m/s @ 41.99 degrees

Relative Velocity Example #23 A motorboat traveling 4 m/s East encounters a current traveling 3.0 m/s, North. C. How far does the boat travel downstream before reaching the shore?

C. The boat travels 60m downstream before reaching the shore

Relative Velocity Example #26 Two sailors are on a whaleboat that travels at a speed 10.0 km/h. They wish to cross a river 2.0 km wide in the quickest time. The speed of the river is 9.0 kms/hr North to the shore. C. How far down river do they travel before they reach the other side?

C. They travel 1.8 km down the river before they reach the other side.

Relative Velocity Example #21 A boat is traveling across a river with a speed of 4 m/s N when it encounters a river which is flowing east with a speed of 2 m/s. If the river is 120m across; C. How far down the stream do you end up?

C. You would end up 60.01m down stream.

Relative Velocity Example #20 The president's airplane, Air Force One, flies at 250 m/s to the east with respect to the air. The air is moving at 35 m/s to the north with respect to the ground. Find the velocity of Air Force One with respect to the ground.

The velocity of Air Force One is 252.4 m/s ^2 @ 7.97 degrees.