Download 1 - Net Start Class

Physics 12 WK DCA Review – Forces & Projectiles
1. Which of the following statements are true of projectiles? List all that apply.
a. A projectile is a free-falling object.
b. A projectile experiences negligible or no air resistance.
c. A projectile must be moving in the downward direction.
d. A projectile must be accelerating in the downward direction.
e. A projectile does not have to have horizontal motion.
f. A projectile could begin its projectile motion with a downward velocity.
g. A projectile does not need to be "falling."
2. Which of the following statements are true of the time of flight for a projectile? List all
that apply.
a. The time that a projectile is in the air is dependent upon the horizontal component
of the initial velocity.
b. The time that a projectile is in the air is dependent upon the vertical component of
the initial velocity.
c. 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.
d. For the same upward launch angles, projectiles will stay in the air longer if the
initial velocity is increased.
e. 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.
3. Vector A is directed northward and vector B is directed eastward. Which of the following
vector addition diagrams best represent the addition of vectors A and B and the
subsequent resultant?
4. What is the velocity of a projectile with a vertical velocity of 25.0 m/s and a horizontal
velocity of 18.0 m/s?
a. 7.00
b. 21.56
c. 30.8
d. 35.8
m/s
m/s
m/s
m/s
5. Which of the following is true for an object in freefall?
a. Speed increases
b. Acceleration increases
Use the following choices to answer questions 6-8.
a. entirely
b. entirely
horizontal
vertical
c. both
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 velocity is ___.
7. 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.)
8. 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, the net force acting upon it is _______. (Neglect the effects
of air resistance.)
9. At what point in its path is the horizontal component of the velocity (vx) of a projectile
the smallest?
10.At what point in its path is the vertical component of the velocity (vy) of a projectile
the smallest?
11.As you roll a bowling ball off a table, what happens to the horizontal component of its
velocity?
12.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.)
13.Two projectiles are fired at equal speeds but different angles. One is fired at angle of
30 degrees and the other at 60 degrees. Which projectile will hit the ground first?
14.Consider the trajectory diagrams shown below for two different projectiles. The first is
launched horizontally, and the second is launched at an angle. On the diagrams, draw
vector arrows representing the vx and vy velocity components during the course of the
motion. The length of the arrows should represent the magnitude of the velocity
components. Label each component. (Note that the velocity components are already
shown for the first position.)
15.The launch velocity and angle is given for three different projectiles. Use trigonometric
functions to resolve the velocity vectors into horizontal (vx) and vertical (vy) velocity
components. Then use kinematic equations to determine the time that the projectile is
in the air, the maximum height, and the range that it travels.
Launch Angle
Launch Velocity
30⁰
30 m/s
45⁰
60⁰
30 m/s
30 m/s
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16.If a projectile is launched horizontally with a speed of 12.0 m/s from the top of a 24.6meter high building. Determine the horizontal displacement of the projectile.
17.A projectile is launched with an initial speed of 21.8 m/s at an angle of 35.0-degrees
above the horizontal.
a. Determine the time of flight of the projectile.
b. Determine the peak height of the projectile.
c. Determine the horizontal displacement of the projectile.
18.A projectile is launched horizontally from the top of a 45.2-meter high cliff and lands a
distance of 17.6 meters from the base of the cliff. Determine the magnitude of the
launch velocity.
19.Construct free-body diagrams for the following physical situations.
a. A ball is dropped from rest from the top of a building. Assume negligible air
resistance.
b. After being thrown, a football is moving upwards and rightwards towards the
peak of its trajectory. Assume negligible air resistance.
c. After reaching a terminal velocity, a falling skydiver then opens up the
parachute.
d. An air track glider (frictionless) is gliding to the right at constant velocity.
e. A car is skidding to a stop while traveling to the right.
20.Which of the following are always true of an object that is at equilibrium?
a. All the forces acting upon the object are equal.
b. The object is at rest.
c. The object is moving and moving with a constant velocity.
d. The object has an acceleration of zero.
e. There is no change in the object's velocity.
f. The sum of all the forces is 0 N.
g. All the forces acting upon an object are balanced.
21.Which of the following are never true of an object that is at equilibrium?
a. The object is accelerating.
b. The object is at rest.
c. The object is moving in a circle at constant speed.
d. All the forces acting upon the object are equal.
e. The object is in free-fall.
f. The object is falling and has reached its terminal velocity.
g. There is a net force acting upon the object.
h. The object is moving and moving with a constant velocity.
i. The object is at rest.
22.How much force is needed to accelerate a car with a mass of 1000 kilograms from a
full stop to 50 m/s in 10 seconds if the rate of acceleration is constant?
a. 1000 N
b. 2000 N
c. 5000 N
d. 10,00N
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23.A car accelerates at a constant rate of 3 m/s2. A continuous force of 3000 N along the
direction of motion is responsible for this acceleration. What is the mass of the car?
a. 3000 kg
c. 1000 kg
b. 9000 kg
d. 500 kg
24.In a tug of war game, one team pulls to the east with a force of 500 N while the other
team pulls west with a force of 300 N. If the ropes of each team are attached to a cart
in the center that has a mass of 50 kg, what will be the acceleration of the cart?
a. 10 m/s2, East
c. 4 m/s2, East
b. 10 m/s2, West
d. 4 m/s2, West
25.According to Newton’s 2nd Law, what is the relationship between mass and
acceleration?
a. mass and acceleration are directly proportional
b. mass and acceleration are inversely proportional
c. there is no relationship
26. Forces F1 and F2 are applied simultaneously to the same point on a large crate resting
on a frictionless surface. Which diagram shows the forces positioned to give the crate
the greatest acceleration?
27.A different force is applied to each of four 1 kg blocks to slide them across a uniform
surface at constant speed as shown below. In which diagram is the coefficient of
friction between the block and the surface the greatest?
28.A rubber ball weighs 49N. It is thrown upward with a force of 89 N. What is the
acceleration of the ball?
a. 30 m/s2
b. 5 m/s2
c. 8 m/s2
d. 4 m/s2
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