PHY2053 - Ch. 3 Practice Problems

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

be over the bomb

For a projectile launched horizontally, the vertical component of a projectile's velocity

continuously increases

A rock is thrown upwards at an angle of 40° with respect to the horizontal. As the rock is rising in its trajectory, the vertical component of its velocity

decreases

Two similar objects are thrown simultaneously from the top of a building with the same speed. One is thrown vertically downward, and the other at an angle. Both objects reach the ground at the same time.

false

The horizontal component of the velocity of a projectile remains constant during the entire trajectory of the projectile.

true

The vertical component of the acceleration of a projectile remains constant during the entire trajectory of the projectile.

true

A bullet is fired from ground level with a speed of 150 m/s at an angle 30.0° above the horizontal at a location where g = 10.0 m/s2. What is the vertical component of its velocity when it is at the highest point of its trajectory?

0 m/s2

A projectile is launched with an initial velocity of 80 m/s at an angle of 30° above the horizontal. Neglecting air resistance, what is horizontal component of the projectile's acceleration?

0 m/s2

For which value of θ is the range of a projectile fired from ground level a maximum?

45° above the horizontal

A ball is thrown with a velocity of 40 m/s at an angle of 30° above the horizontal and attains a certain range R. At what other angle will this ball attain the same range keeping its initial velocity the same?

60°

A boy kicks a football with an initial velocity of 20 m/s at an angle of 25° above the horizontal. The magnitude of the acceleration of the ball while it is in flight is

9.8 m/s2

For which value of θ is the height of a projectile fired from ground level a maximum?

90° above the horizontal

A rock is thrown from ground level at some angle above the horizontal with a certain velocity. It reaches its highest point and starts falling down. What is the magnitude of the velocity of the rock right before it hits the ground?

It is equal to the magnitude of its initial velocity.

When a football in a field goal attempt reaches its maximum height, how does its speed compare to its initial speed?

It is less than its initial speed.

A projectile is launched with initial velocity v0 at an angle of 30° above the horizontal. If a second projectile is launched with the same initial velocity but at angle of 60° above the horizontal

The ranges of the two projectiles will be identical

An athlete throws a ball with a velocity of 40 m/s at an angle of 20° above the horizontal. Which of the following statements is true in this case?

The vertical component of the velocity changes sign after the ball attains its maximum height

For general projectile motion, the horizontal component of a projectile's acceleration

is zero

A rock is thrown at some angle above the horizontal with a certain velocity. It reaches its highest point and starts falling down. What is the velocity of the rock at the highest point of its trajectory?

it is equal to its initial horizontal velocity

If the initial speed of a projectile is doubled.

its range will quadruple.

A student kicks a soccer ball in a high arc toward the opponent's goal. At the highest point in its trajectory:

neither the ball's velocity nor its acceleration is zero

For a projectile launched horizontally, the horizontal component of a projectile's velocity

remains a non-zero constant

For general projectile motion, the horizontal component of a projectile's velocity

remains a non-zero constant

For general projectile motion, the vertical component of a projectile's acceleration

remains a non-zero constant

A rock is thrown upwards at an angle of 40° with respect to the horizontal. As the rock is rising in its trajectory, the horizontal component of its velocity

remains the same

If the acceleration vector of an object is directed parallel to the velocity vector,

the object is speeding up

If the acceleration vector of an object is directed perpendicular to the velocity vector,

the object is turning

James and John dive from an overhang into the lake below. James simply drops straight down from the edge. John takes a running start and jumps with an initial horizontal velocity of 25 m/s. When they reach the lake below,

the splashdown speed of John is larger than that of James

A ball is thrown at an angle of θabove the horizontal. If there is no acceleration due to gravity the ball will follow a straight-line path.

true

A projectile is launched from ground level with a certain speed. For any range less than the maximum range there are two possible launch angles that give the same range.

true