Physics Chapter 3

Vector A has a magnitude of 30 units. Vector B is perpendicular to vector A and has a magnitude of 40 units. What would the magnitude of the resultant vector A + B be?

• 10 units

• 50 units

• 70 units

• zero

What term represents the magnitude of a velocity vector?

• acceleration

• momentum

• speed

• velocity

What is the direction of the resultant vector A + B?

• 15° above the x-axis

• 75° above the x-axis

• 15° below the x-axis

• 75° below the x-axis

What is the direction of the resultant vector A - B?

• 15° above the x-axis

• 75° above the x-axis

• 15° below the x-axis

• 75° below the x-axis

A motorboat heads due east at 5.0 m/s across a river that flows toward the south at a speed of 5.0 m/s. What is the resultant velocity relative to an observer on the shore?

• 3.2 m/s to the southeast

• 5.0 m/s to the southeast

• 7.1 m/s to the southeast

• 10.0 m/s to the southeast

If the river is 125 m wide, how long does the boat take to cross the river?

• 39 s

• 25 s

• 17 s

• 12 s

The pilot of a plane measures an air velocity of 165 km/h south relative to the plane. An observer on the ground sees the plane pass overhead at a velocity of 145 km/h toward the north. What is the velocity of the wind that is affecting the plane relative to the observer?

• 20 km/h to the north

• 20 km/h to the south

• 165 km/h to the north

• 310 km/h to the south

A golfer takes two putts to sink his ball in the hole once he is on the green. The first putt displaces the ball 6.00 m east, and the second putt displaces the ball 5.40 m south. What displacement would put the ball in the hole in one putt?

• 11.40 m southeast

• 8.07 m at 48.0° south of east

• 3.32 m at 42.0° south of east

• 8.07 m at 42.0° south of east

A girl riding a bicycle at 2.0 m/s throws a tennis ball horizontally forward at a speed of 1.0 m/s from a height of 1.5 m. At the same moment, a boy standing on the sidewalk drops a tennis ball straight down from a height of 1.5 m.

What is the initial speed of the girl's ball relative to the boy?

• 1.0 m/s

• 1.5 m/s

• 2.0 m/s

• 3.0 m/s

A girl riding a bicycle at 2.0 m/s throws a tennis ball horizontally forward at a speed of 1.0 m/s from a height of 1.5 m. At the same moment, a boy standing on the sidewalk drops a tennis ball straight down from a height of 1.5 m.

If air resistance is disregarded, which ball will hit the ground first?

• the boy's ball

• the girl's ball

• neither

• cannot be determined