Relative Velocity

What is the relative velocity of the arrow according to the girl in the red shirt?

• 300 km/hr

• 200 km/hr

• 100 km/hr

Answer explanation

To the girl , the arrow is already moving at 100km/hr because of the train, then he shoots the arrow 200km/hr, as if he pushed it ahead faster. You would add these magnitudes together. 100+200=300 km/hr

What is the relative velocity of the arrow according to the guy shooting the arrow?

• 300 km/hr

• 200 km/hr

• 100 km/hr

Answer explanation

To the guy , the arrow is already at rest, because he is on the train moving at 100km/hr. When he shoots the arrow, it moves away from him at 200km/hr.

So to him, it is moving at 200km/hr.

What is the relative speed of the guy walking on the belt to the girl standing still on the walkway.

• 0 m/s

• 2 m/s

• 4 m/s

• 1 m/s

Answer explanation

The belt is moving at a rate of 2 m/s. The guys is walking on the belt moving at 2 m/s ON TOP OF the already moving 2 m/s. So these two speeds add together. 2+2 = 4 m/s

A dog and a cat are about to fight, running towards each other, both at 12 m/s. What are their velocities relative to each other?

• 12 m/s

• 24 m/s

• 0 m/s

• 6 m/s

What is the walker's speed with respect to the train?

• 30 mph

• 10 mph

• 40 mph

• 50 mph

Observers using different ___________________ may measure different velocities for an object in motion

• frame of reference

• relatives of motion

• projectile motions

• constant velocity

What is the walker's speed from the observer's perspective?

• 10 mph

• 40 mph

• 50 mph

• 30 mph

What is the train's speed with respect to the stationary observer?

• 40 mph

• 50 mph

• 10 mph

• 30 mph

A boat heading north crosses a wide river with a velocity of 10.00 km/h relative to the water. The river has a uniform velocity of 5.00 km/h due east. What formula would you used to Determine the boat’s speed with respect to an observer on shore.

• subtraction (10-5)

• addition (10+5)

• division (10/5)

• Pythagorean Theorem (A² + B² = C²)

• Multiplication (10*5)

Answer explanation

A boat heading north crosses a wide river with a velocity of 10.00 km/h relative to the water. The river has a uniform velocity of 5.00 km/h due east. Determine the boat’s speed with respect to an observer on shore.

• 11.18 km/hr

• 15 km/hr

• 5 km/hr

• 30 km/hr

Answer explanation

Use the Pythag. Theorem to solve for the velocity. the numbers in the example are NOT from the problem above.