Chapter 4

Shown below are the velocity and acceleration vectors for a person in several different types of motion. In which case is the person slowing down and turning to his right

(a) Angled Left and (v) Down

A monkey is sitting at the top of a tree 20 m above ground level. A person standing on the ground wants to feed the monkey. He uses a bow and arrow to launch the food to the monkey. If the person knows that the monkey is going to drop from the tree at the same instant that the person launches the food, how should the person aim the arrow containing the food? Air resistance is small enough to be ignored.

Aim at the monkey

A pilot drops a package from a plane flying horizontally at a constant speed. Neglecting air resistance, when the package hits the ground the horizontal location of the plane will

Be over the package

Jan and Len throw identical rocks off a tall building at the same time. The ground near the building is flat. Jan throws her rock straight downward. Len throws his rock downward and outward such that the angle between the initial velocity of the rock and the horizon is 30°. Len throws the rock with a speed twice that of Jan's rock. If air resistance is negligible, which rock hits the ground first?

Same time

lice and Tom dive from an overhang intothe lake below. Tom simply drops straight down from the edge, but Alice takes a running start and jumps with an initial horizontal velocity of 25 m/s. Neither person experiences any significant air resistance. Compare the time it takes each of them to reach the lake below.

Same time

While an object is in projectile motion (with upward being positive) with no air resistance

The horizontal component of its velocity remains constant and the vertical component of its acceleration is equal to -g.

For an object in uniform circular motion, its velocity and acceleration vectors are always perpendicular to each other at every point in the path

True

For general projectile motion, when the projectile is at the highest point of its trajectory

Velocity is perpendicular to accel

If an object travels at a constant speed in a circular path, the acceleration of the object is

larger in amagnitude the smaller the radius

Alice and Tom dive from an overhang into the lake below. Tom simply drops straight down from the edge, but Alice takes a running start and jumps with an initial horizontal velocity of 25 m/s. Neither person experiences any significant air resistance. Just as they reach the lake below

the speed of Alice is larger than that of Tom.

Point Pin the figure indicates the position of an object traveling at constant speed clockwisearound the circle. Which arrow best represents the direction of the acceleration of the object at point P?

towards center

If you set the cruise control of your car to a certain speed and take a turn, the speed of the car will remain the same. Is the car accelerating?

yes