Projectile Motion Quiz

T/F A ball will go the farthest if thrown almost horizontally.

False

T/F A quantity that has both a magnitude and direction is called scalar

False

T/F A quantity that has only magnitude is called a vector.

False

T/F A single vector can be replaced by two vectors in the x- and y-directions that are at right angles to each other. These two x and y vectors are called the resultants of the original vector.

False

T/F Mass is a vector quantity.

False

T/F When adding two vectors at right angles, the resultant of the vectors is the algebraic sum of the two vectors.

False

T/F Any vector can be represented by two other vectors that are at right angles to each other.

True

T/F The length of a vector represents its magnitude.

True

T/F The orientation of a vector shows its direction.

True

T/F The vector sum is called the resultant.

True

T/F Wind velocity can be represented as a vector quantity.

True

In the absence of air resistance, at what other angle will a thrown ball go the same distance as one thrown at an angle of 75 degrees? a. 15 degrees. b. 65 degrees. c. 70 degrees. d. 80 degrees. e. 90 degrees.

a. 15 degrees

A cannon with a barrel velocity of 140 m/s launches a cannonball horizontally from a tower. Neglecting air resistance, how far vertically will the cannonball have fallen after 4 seconds? a. 80 m b. 140 m c. 560 m d. 2240 m e. none of the above

a. 80 m

In the absence of air friction, the vertical component of a projectile's velocity doesn't change as the projectile moves a. Always false b. Always true c. Sometimes true

a. Always false

At the instant a ball is thrown horizontally with a large force, an identical ball is dropped from the same height. Which ball hits the ground first? a. Neither—they both hit the ground at the same time. b. The horizontally thrown ball c. The dropped ball

a. Neither- they both hit the ground at the same time

At the instant a ball is thrown horizontally with a large force, an identical ball is dropped from the same height. Which ball hits the ground first? a. Neither. They both hit the ground at the same time b. The dropped ball c. The horizontally thrown ball

a. Neither. They both hit the ground at the same time

An airplane flying into a head wind loses ground speed, and an airplane flying with the wind gains ground speed. If an airplane flies at right angles to the wind, then ground speed is a. more b. unchanged c. less

a. more

In Chapter 2, you learned about "hang time," the time a jumper's feet are off the ground in a vertical jump. If the jumper runs horizontally and has the same vertical component of takeoff velocity, hang time will be a. no different. b. decreased. c. increased.

a. no different

Jose can jump vertically 1 meter from his skateboard when it is at rest. When the skateboard is moving horizontally, Jose can jump a. no higher b. higher

a. no higher

When in orbit, a satellite such as the space shuttle is a. simply a projectile. b. in non-accelerated motion. c. free from Earth's gravity.

a. simply a projectile

A projectile launched horizontally hits the ground in 0.8 seconds. If it had been launched with a much higher speed in the same direction, it would have hit the ground (neglecting Earth's curvature and air resistance) in a. more than 0.8 s. b. 0.8 s. c. less than 0.8 s.

b. 0.8 s

What is the resultant of a 3-unit vector and 4-unit vector at right angles to each other? a. 1 unit. b. 5 units. c. 7 units. d. none of the above

b. 5 units

Which of the following would NOT be considered a projectile? a. A cannonball thrown straight up b. A cannonball rolling down a slope c. A cannonball rolling off the edge of a table d. A cannonball thrown through the air e. All of the above are projectils

b. A cannonball rolling down a slope

In the absence of air friction, the horizontal component of a projectile's velocity doesn't change at the projectile moves a. Sometimes true b. Always true c. Always false

b. Always true

If you could throw a baseball horizontally at a speed of 8 km/s and if there were no air drag and nothing to stop it, a. after 90 minutes it would return to you. b. it would orbit Earth. c. it would escape Earth's atmosphere.

b. it would orbit Earth

A scalar is a quantity that has a. direction b. magnitude c. time d. color

b. magnitude

A ball is thrown straight upward at 10 m/s. Ideally (no air resistance), the ball will return to the thrower's hand with a speed of a. 0 m/s. b. 5 m/s. c. 10 m/s. d. 20 m/s. e. There is not enough information to say.

c. 10 m/s

A cannonball is launched from the ground at an angle of 30 degrees above the horizontal and a speed of 30 m/s. Ideally (no air resistance) the ball will land on the ground with a speed of a. 0 m/s. b. 20 m/s. c. 30 m/s. d. 40 m/s. e. There is not enough information to say.

c. 30 m/s

In the absence of air resistance, the angle at which a thrown ball will go the farthest is a. 15 degrees b. 30 degrees c. 45 degrees. d. 60 degrees. e. 75 degrees.

c. 45 degrees

A cannonball is fired at some angle into the air. In the first second it moves 5 meters horizontally. Assuming it doesn't hit the ground and air resistance is negligible, how far does it move horizontally in the next second? a. More than 5 m b. Less than 5 m c. 5 m d. Not enough information.

c. 5 m

A cannonball is launched horizontally from a tower. If the cannon has a barrel velocity of 60 m/s, where will the cannonball be 1 second later? (Neglect air resistance.) a. 6 m downrange b. 30 m downrange c. 60 m downrange d. 300 m downrange e. none of the above

c. 60 m downrange

Which best approximates the resultant of a pair of 6-unit vectors at right angles to each other? a. 0 units b. 6 units c. 8 units d. 12 units

c. 8 units

At what part of a path does a projectile have minimum speed? a. When it returns to the ground b. Halfway to the top c. At the top of its path d. When it is thrown e. There's not enough information to say.

c. At the top of its path

A vector is a quantity that has a. magnitude and time b. time and direction c. magnitude and direction

c. magnitude and direction

After a rock that is thrown straight up reaches the top of its path and is starting to fall back down, its acceleration is (neglecting air resistance) a. less than when it was at the top of its path. b. greater than when it was at the top of its path. c. the same as when it was at the top of its path.

c. the same as when it was at the top of its path

The horizontal component of a projectile's velocity is independent of a. the range of the projectile. b. time. c. the vertical component of its velocity.

c. the vertical component of its velocity

A baseball is hurled into the air at an angle of 30 degrees above the horizontal and lands on a target that is at the same level as that where the baseball started. The baseball will also land on the target if it is thrown at an angle of a. 20 degrees. b. 40 degrees. c. 50 degrees. d. 60 degrees. e. none of the above

d. 60 degrees

In order to find the components of a vector, you should a. draw the vector with correct magnitude and orientation. b. measure the sides of the rectangle. c. draw a rectangle so that the vector is the diagonal. d. all of the above

d. all of the above

When representing velocity as a vector a. the direction of the arrow shows the direction of motion b. the length of the arrow represents the speed c. the length of the arrow is drawn to a suitable scale d. all of the above e. none of the above

d. all of the above

A ball is thrown into the air at some angle. At the very top of the ball's path, its velocity is a. entirely vertical b. There's not enough information given to determine c. both vertical and horizontal d. entirely horizontal

d. entirely horizontal

An object is dropped and falls freely to the ground with an acceleration of g. If it is thrown upward at an angle instead, its acceleration would be a. 0 b. larger than g c. g upward d. g downward e. none of the above

d. g downward

A projectile is fired horizontally in a vacuum. The projectile maintains its horizontal component of speed because it a. has no vertical component of speed to begin with. b. is not acted on by any forces. c. the net force acting on it is zero. d. is not acted on by any horizontal forces. e. none of the above

d. is not acted on by any horizontal forces

Suppose a small plane can fly at 170 km/h relative to the surrounding air. Suppose also that there is a 60 km/h tailwind. How fast does the plane's shadow move across the ground? a. 5 km/h b. 60 km/h c. 110 km/h d. 170 km/h e. 230 km/h

e. 230 km/h

A ball thrown in the air will never go as far as physics ideally would predict because a. one can never throw the ball fast enough b. gravity is acting c. air friction slows the ball d. ideally the ball would never land e. all of the above

e. all of the above