Projectile Motion
If the net external force acting on an object is constant what must be true about the object's acceleration?
Acceleration must be constant
What is linear momentum?
Quantity of motion possessed by an object
A soccer ball leaves the ground with an initial horizontal velocity of 19.7 m/s and is in the air for 1.58s. How far will the ball travel?
31.13 m
What is the vertical acceleration of the COM of an 86.3 kg person performing a vertical jump from a
force plate at an instant in time when the force measured by a force plate is Fx = 367 N and
Fy = 2350?
ay = 17.45 m/s^2
A football is kicked two times. During the first kick, the football has a resultant velocity of
27.4 m/s and angle of projection of 30° (CCW with respect to the right horizontal). During the
second kick, the football has the same resultant velocity (27.4 m/s), but an angle of
projection of 45° (CCW with respect to the right horizontal). The ____ kick will travel higher
(vertical displacement) because the ____. (Assume the release and landing height are equal
and the same for both kicks and ignore the influence of air resistance
A) first : initial horizontal velocity will be greater
B) first: vertical acceleration will be greater
C) second: vertical acceleration will be greater
D) second: initial vertical velocity will be greater
E) The two kicks will have the same vertical displacement because they have the same resultant velocities.
D) second: initial vertical velocity will be greater
-9.81 m/s^2
A non-zero centric external force is applied to an object over a period of time in the opposite direction of the object. What will happen to the linear momentum of the object?
Decrease
A volleyball setter sets a ball for a spiker. The ball leaves the setter’s fingers 2.1 m above the
ground with an initial vertical velocity of 2.2 m/s. How high will the ball travel?
2.35 m
What horizontal impulse was produced by a 58.0 kg swimmer whose horizontal velocity just after leaving the starting block was 4.2 m/s?
243.6 Ns
A shot just left a shot putter’s hand with an initial vertical velocity of 6.5 m/s and an initial
horizontal velocity of 11.1 m/s. At the highest point in the shot put trajectory, the horizontal velocity of the shot will be _____. (ignore the influence of air resistance)
A) -9.81 m/s 2
B) 11.1 m/s
C) 6.5 m/s
D) 9.81 m/s 2
E) 0 m/s
B) 11.1 m/s
A baseball is hit with an initial horizontal velocity of 30 m/s and an initial vertical velocity of 12 m/s. What is the vertical velocity of the baseball at peak vertical height?
0 m/s
How can linear momentum of an object be increased? (2 answers)
Increase net external force
Increase time the force is acting
A soccer ball leaves the ground with an initial vertical velocity of 10 m/s and travels 50 m. What was the initial horizontal velocity of the ball?
49.02 m/s
What is the average resultant external force provided by a landing pad that stops a 60 kg athlete who hits the mat at -12 m/s and comes to a stop in 1.1 s? What would the average force be if the athlete would have come to a stop in 0.5s?
F2 = 1440 N
Two hockey players (skater 1 and skater 2), skating toward each other, collide and stick
together after the collision. If both players are defined as the system of interest, and friction at
the skate-ice interface is ignored, which of the following statements is true?
A) The linear momentum of skater 1 will be equal before and after the collision
B) The total linear momentum of the system of interest will be equal before and after the
collision
C) The linear momentum of skater 2 will be equal before and after the collision.
D) The total linear momentum of the system of interest will be increased after the
collision
E) The total linear momentum of the system of interest will be decreased after the
collision
B) The total linear momentum of the system of interest will be equal before and after the
collision
Yes, weight does not affect trajectory
Brewers are down by 1 with 2 outs, 2 runners on, bottom of the 9th. Christian Yelich at the plate hits the ball toward right field with and exit velocity of 50 m/s and a launch angle of 23 degrees. Ignoring air resistance How far does the ball travel? Do the Brewers Win?
183 m (600 ft)
At an instant in the early portion of a sprinter’s race, the GRF acting on a sprinters foot is
1672.1 N. The GRF acts on the sprinter’s foot at an angle of 53.22° CCW with respect to the
right horizontal. The sprinter weighs 680 N. What is the sprinter’s horizontal acceleration at
this instant in time? Vertical acceleration?
ax = 14.44 m/s^2
ay = 9.5 m/s^2
An individual (Weight: 500 N) is performing a countermovement jump while standing on a
force plate. At an instant in the beginning of the countermovement portion of the jump (the
individual has just started flexing the hips and knees and dorsiflexing the ankles), the force
plate reads 450 N. Given this information, you know that the individual _____. Assume the
typical XY coordinate system.
A) Not enough information is given to answer the question.
B) is moving in the positive direction and speeding up
C) is moving in the negative direction and slowing down
D) has come to a stop
E) is moving in the negative direction and speeding up
E) is moving in the negative direction and speeding up
During a standing long jump an individual (80kg) produces an impulse of 295 Ns horizontally and 225 Ns vertically. What will the peak height of the trajectory be, and how far will they jump?
peak height = 0.4m
distance = 2.14m
An individual kicks (applies a force to) a soccer ball. Given this information, we know that there will be ______.
A) an equal magnitude force acting from the ball onto the player’s kicking limb in the
opposite direction as the applied kicking force, and the accelerations of the ball and
the player’s kicking limb will be equal
B) an equal magnitude force acting from the ball onto the player’s kicking limb in the
opposite direction as the applied kicking force, but the accelerations of the ball and
the player’s kicking limb will not be equal
C) a greater magnitude force acting from the ball onto the player’s kicking limb in the
opposite direction as the applied kicking force, but the accelerations of the ball and
the player’s kicking limb will be equal
D) a lower magnitude force acting from the ball onto the player’s kicking limb in the
opposite direction as the applied kicking force, but the accelerations of the ball and
the player’s kicking limb will not be equal
B) an equal magnitude force acting from the ball onto the player’s kicking limb in the
opposite direction as the applied kicking force, but the accelerations of the ball and
the player’s kicking limb will not be equal