Physics test #2

Not a projectile

a cannonball rolling down a slope

Not an example of projectile motion

a hot-air balloon drifting toward Earth

What doesnt exhibit parabolic motion

a piece of paper released from a window

In the absence of air resistance the vertical component of a projectiles vel doesnt change as the projectile moves

always false;gravity

An object moving in the air not touching anything is a projectile

false

Mass is a vector quantity

false

a falling feather is a projectile

false

a falling skydiver with an open parachte is a projectile

false

a projectile must be moving in the downward direction

false

a projectile with an upward component of motion will have an upward component of acceleration

false

any object where air resistance is negligiable is a projectile

false

Airplane flying with right angle to the wind what happens to speed

increases is more

which is a physical quantity that has mag and direction

momentum

if vectors a and b are added at right angles to each other then one can be sure that the resultant will have a mag of either one of the individual vectors? true? false?

False

max possible resultant pair of vectors 4 and 6

10

Least possible resultant pair of vectors 4 and 6

2

45. Two projectiles are fired at equal speeds but different angles. One is fired at angle of 30 degrees and the other at 60 degrees. The projectile to hit the ground first will be the one fired at (neglect air resistance) ____. a. 30 degrees b. 60 degrees c. both hit at the same time

A

6. A football is kicked into the air at an angle of 45 degrees with the horizontal. At the very top of the ball's path, its acceleration is _______. (Neglect the effects of air resistance.) a. entirely vertical b. entirely horizontal c. both vertical and horizontal d. not enough information given to know.

A

An object is undergoing free fall motion. As it falls, the object's ____. a. speed increases b. acceleration increases c. both of these d. none of these

A

6. Which of the following statements are true of projectiles? List all that apply. A projectile is a free-falling object. A projectile experiences negligible or no air resistance. A projectile must be moving in the downward direction. A projectile must be accelerating in the downward direction. A projectile does not have to have horizontal motion. A projectile could begin its projectile motion with a downward velocity. A projectile does not need to be "falling."

ABDEF G

3. Numerical values and directions are stated for a variety of quantities. Which of these statements represent a vector description? Include all that apply. 20 meters, west 9.8 m/s/s 35 mi/hr, south 16 years old 60 minutes 3.5 m/s/s, south -3.5 m/s/s +20 degrees C

ACFG

In the absence of air friction, the horizontal component of a projectile's velocity doesn't change as the projectile moves

Always true; gravity is a vertical component and air resistance doesnt change as a horizontal component

42. Roll a bowling ball off the edge of a table. As it falls, its horizontal component of velocity ___. a. decreases b. remains constant c. increases

B

9. Which of the following statements are true of the time of flight for a projectile? List all that apply. The time that a projectile is in the air is dependent upon the horizontal component of the initial velocity. The time that a projectile is in the air is dependent upon the vertical component of the initial velocity. For a projectile which lands at the same height that it is projected from, the time to rise to the peak is equal to the time to fall from its peak to the original height. For the same upward launch angles, projectiles will stay in the air longer if the initial velocity is increased. Assume that a kicked ball in football is a projectile. If the ball takes 3 seconds to rise to the peak of its trajectory, then it will take 6 seconds to fall from the peak of its trajectory to the ground.

BCD

2. Which of the following quantities are vectors? Include all that apply. a distance traveled b displacement c average speed d average velocity e instantaneous velocity f acceleration

BDEF

. At what point in its path is the vertical component of the velocity (vy) of a projectile the smallest? a. The instant it is thrown. b. Halfway to the top. c. At the top. d. As it nears the top. e. It is the same throughout the path.

C

43. A bullet is fired horizontally and hits the ground in 0.5 seconds. If it had been fired with twice the speed in the same direction, it would have hit the ground in ____. (Assume no air resistance.) a. less than 0.5 s. b. more than 0.5 s. c. 0.5 s.

C

. Which of the following statements are true of the vertical motion of projectiles? List all that apply. The vertical component of a projectile's velocity is a constant value of 9.8 m/s. The vertical component of a projectile's velocity is constant. The vertical component of a projectile's velocity is changing. The vertical component of a projectile's velocity is changing at a constant rate. A projectile with an upward component of motion will have a upward component of acceleration. A projectile with an downward component of motion will have a downward component of acceleration. The magnitude of the vertical velocity of a projectile changes by 9.8 m/s each second. The vertical velocity of a projectile is 0 m/s at the peak of its trajectory. The vertical velocity of a projectile is unaffected by the horizontal velocity; these two components of motion are independent of each other. The final vertical velocity of a projectile is always equal to the initial vertical velocity. The vertical acceleration of a projectile is 0 m/s/s when it is at the peak of its trajectory. As a projectile rises towards the peak of its trajectory, the vertical acceleration will decrease; as it falls from the peak of its trajectory, its vertical acceleration will decrease. As a projectile rises towards the peak of its trajectory, the vertical acceleration is directed upward; as it falls from the peak of its trajectory, its vertical acceleration is directed downward. The peak height to which a projectile rises above the launch location is dependent upon the initial vertical velocity. As a projectile rises towards the peak of its trajectory, the vertical velocity will decrease; as it falls from the peak of its trajectory, its vertical velocity will decrease. Consider a projectile launched from ground level at a fixed launch speed and a variable angle and landing at ground level. The vertical displacement of the projectile during the first half of its trajectory (i.e., the peak height) will always increase as the angle of launch is increased from 0 degrees to 90 degrees. Consider a projectile launched from ground level at a fixed launch angle and a variable launch speed and landing at ground level. The vertical displacement of the projectile during the first half of its trajectory (i.e., the peak height) will always increase as the launch speed is increased.

CDFGHINPQ

10. If two displacement vectors of 6 meters and 8 meters (with varying directions) are added together, then the resultant could range anywhere between ___ meters and ___ meters. a. 0, 48 b. 1.33, 48 c. 0, 14 d. 2, 14

D

44. A projectile is launched at an angle of 15 degrees above the horizontal and lands down range. For the same speed, what other projection angle would produce the same downrange distance? a. 30 degrees. b. 45 degrees. c. 50 degrees. d. 75 degrees e. 90 degrees.

D

5. Which of the following descriptions of moving objects accurately portray a projectile? List all that apply. an object which is moving through the air and not touching any surface a falling skydiver with an open parachute any object upon which air resistance is negligible a free-falling object an object upon which the only significant force is the force of gravity a falling feather a falling feather in a vacuum chamber a falling feather in a falling vacuum chamber.

DEGH

7. Which of the following statements are true of the horizontal motion of projectiles? List all that apply. A projectile does not have a horizontal velocity. A projectile with a rightward component of motion will have a rightward component of acceleration. The horizontal velocity of a projectile changes by 9.8 m/s each second. A projectile with a horizontal component of motion will have a constant horizontal velocity. The horizontal velocity of a projectile is 0 m/s at the peak of its trajectory. The horizontal velocity of a projectile is unaffected by the vertical velocity; these two components of motion are independent of each other. The horizontal displacement of a projectile is dependent upon the time of flight and the initial horizontal velocity. The final horizontal velocity of a projectile is always equal to the initial horizontal velocity. As a projectile rises towards the peak of its trajectory, the horizontal velocity will decrease; as it falls from the peak of its trajectory, its horizontal velocity will decrease. Consider a projectile launched from ground level at a fixed launch speed and a variable angle and landing at ground level. The horizontal displacement (i.e., the range) of the projectile will always increase as the angle of launch is increased from 0 degrees to 90 degrees. Consider a projectile launched from ground level at a fixed launch angle and a variable launch speed and landing at ground level. The horizontal displacement (i.e., the range) of the projectile will always increase as the launch speed is increased.

DFGHK

. At what point in its path is the horizontal component of the velocity (vx) of a projectile the smallest? a. The instant it is thrown. b. Halfway to the top. c. At the top. d. As it nears the top. e. It is the same throughout the path.

E

33. If the current on a particular day was flowing with two times the velocity, then the time to cross the river would be ____. a. two times greater b. one-half as great c. greater, but not two times greater d. less, but not one-half the original time e. the same as it was when the current flowed at 1.8 m/s.

E

vector sum

resultant

what term represents mag of vel. vector

speed

a falling feather in a vaccumm chamber is a projectile

true

a free falling object is a projectle

true

a projectile could begin its projectile motion with a downward vel

true

a projectile does not have to have a horizotal motion

true

a projectile must be accelerating in the downward direction

true

a single vector can be replaced by two vectors in the x,y directions that are right angles to eachother

true

an object with only the force of gravity is a projectile

true

the orientation of a vector shows its direction

true

the vector sum of two or more vectors is called the resultant

true

wind velocity can be represented as a vector quantity

true

the horizontal component of a projectiles vel is independent of the what

vertical component to its velocity