(Multiple Choice)

(1)

A river is 0.76 km wide. The banks are straight and parallel (Figure 3-34). The current is 5.0 km/h and is parallel to the banks. A boat has a maximum speed of 3 km/h in still water. The pilot of the boat wishes to go on a straight line from A to B, where AB is perpendicular to the banks. The pilot should

(a) Head directly across the river.

(b) Head 68? upstream from the line AB.

(c) Head 22? upstream from the line AB.

(d) Give up---the trip from A to B is not possible with this boat.

(e) Do none of the above.

(2)

True or false:

When a bullet is fired horizontally, it takes the same amount of time to reach the ground as a bullet dropped from rest from the same height.

(3)

A golfer drives her ball from the tee a distance of 240 yards down the fairway in a high arcing shot. When the ball is at the highest point of its flight,

(a) Its velocity and acceleration are both zero.

(b) Its velocity is zero but its acceleration is nonzero.

(c) Its velocity is nonzero but its acceleration is zero.

(d) Its velocity and acceleration are both nonzero.

(e) Insufficient information is given to answer correctly.

(4)

A projectile was fired at 35^o above the horizontal. At the highest point in its trajectory, its speed was 200 m/s. The initial velocity had a horizontal component of

(a) 0.

(b) (200 cos 35^o) m/s.

(c) (200 sin 35^o) m/s.

(d) (200/cos 35^o) m/s.

(e) 200 m/s.

(5)

Figure represents the parabolic trajectory of a ball going from A to E. What is the direction of the acceleration at point B?

(a) Up and to the right

(b) Down and to the left

(c) Straight up

(d) Straight down

(e) The acceleration of the ball is zero.

(6) True or false:

(a) The magnitude of the sum of two vectors must be greater than the magnitude of either vector.

(b) If the speed is constant, the acceleration must be zero.

(c) If the acceleration is zero, the speed must be constant.

Transcribed Image Text:

5.0 km/h 0.76 km current Max speed 3.0 km/h