1) A car travels from Austin to San Antonio ( 80 miles) with a
velocity of 55 mi/hr. How long does this trip take?
2) A bicyclist cycles from Rohnert Park to the Sonoma/ Marin
county line ( 15 miles) with a velocity of 30 mi/hr. How long
does the trip take?
3) A runner runs around a lake ( 60 miles in circumference) at a
rate of 4 miles/hr. How long does the trip take?
4) How much average acceleration is necessary to slow a car down
from 55 mi/hr to 35 mi/hr in 20 sec?
5) How much average acceleration is necessary to slow down a
truck from 60 to 30 mi/hr in 15 sec?
6) How much average acceleration is necessary to slow down a
bicyclist from 30 to 20 mi/hr in 40 sec?
7) How much average acceleration is necessary for a car to reach
60 mi/hr from a standing start in one minute?
8) How much average acceleration is necessary for a horse to
reach a gallop 20 mi/hr from a trot 5 mi/hr is 5 sec?
9) How much average acceleration is necessary for a swimmer to
reach 12 mi/hr from 2 mi/hr in 20 sec?
10) An object is dropped from a height of 555 ft. How long will
it take for the object to reach the ground?
11) An object is dropped from a bridge (300 ft). How long will
it take to reach the ground?
12) How long does it take for an object dropped from the statue
of liberty (700 ft) to reach the ground?
13) If a ball is dropped from a height of 100 ft, how fast is it
going when it hits the ground/
14) If an apple is dropped from an airplane (40,000 ft), how
fast is it going when it hits the ground?
15) If a jelly bean drops to the ground from a height of 4 ft,
how fast is it going when it hits the ground?
16) A football is kicked at an angle of 30 degrees from the
horizontal with an initial velocity of 50 ft/sec. What are the
horizontal and vertical velocities?
17) A baseball is hit at an angle of 60 degrees to the horizontal
with an initial velocity of 40 ft/min. What are the horizontal
and vertical components of the initial velocity?
18) A javelin at an angle of 45 degrees to the horizontal with an
initial velocity of 70 ft/sec. What are the horizontal and
vertical components of the initial velocity?
19) Two forces are applied to an object at the same time: a
vertical force accelerates the object 3 ft/sec2 and a horizonal
force accelerate the object 4 ft/sec2. What is the resultant
acceleration of the combined forces?
20) Two forces are applied to an object at the same time: a
vertical force accelerates the object 5 ft/sec2 and a horizonal
force accelerate the object 12 ft/sec2. What is the resultant
acceleration of the combined forces?
21) Two forces are applied to an object at the same time: a
vertical force accelerates the object 15 ft/sec2 and a horizonal
force accelerate the object 20 ft/sec2. What is the resultant
acceleration of the combined forces?
22) An athlete is able to leave the ground with an initial
velocity of 16 ft/sec. a) How high can he jump straight up? b)
How high will he go if he jumps at an angle of 30 degrees to the
horizontal?
23) An athlete is able to jump with an initial velocity of 64
ft/sec. a) How high can she jump straight up? b) How high will
she go if she jumps at an angle of 60 degrees to the horizontal?
24) Two athletes jump with an initial velocity of 8 ft/sec. a)
How high can they jump straight up? b) How high will they go if
they jump at an angle of 30 degrees to the horizontal?
25) A basketball player driving in for a layup leaves the ground
at an angle of 30 degrees to the horizontal with a velocity of 32
ft/sec. A defensive player goes straight up to block the shot
with a velocity of 20 ft/sec. a) Which player jumps higher? b)
How long is each player in the air?
26) A basketball player driving in for a layup leaves the ground
at an angle of 60 degrees to the horizontal with a velocity of 48
ft/sec. A defensive player goes straight up to block the shot
with a velocity of 40 ft/sec. a) Which player jumps higher? b)
How long is each player in the air?
27 A basketball player driving in for a layup leaves the ground
at an angle of 45 degrees to the horizontal with a velocity of 16
ft/sec. A defensive player goes straight up to block the shot
with a velocity of 30 ft/sec. a) Which player jumps higher? b)
How long is each player in the air?
28) A shot put coach tries to get his athletes to put the shot at
45 degrees to the horizontal. His best putter releases the shot 8
ft above the ground with an initial velocity of 40 ft/sec. How
would his performance change if he adopted a release angle of 41
degrees to the horizontal.
29) A hockey player push passes a ball at an angle of 35 degrees
to the horizontal. The ball attain a maximum height of 6 ft above
the ground with an initial velocity of 15 ft/sec. How would her
performance change if the release angle was 23 degrees to the
horizontal.
30) A golf player wants a golf ball to leave the ground at a 33
degree angle to the horizontal. The ball leaves the ground with
an initial velocity of 50 ft/sec and achieves a maximum height of
80 ft. How would her performance change if the release angle was
45 degrees to the horizontal.
31) A tennis ball is dropped onto the floor from a height of 4
ft. It rebounds to a height of 3 ft. If the ball was in contact
with the floor for 0.01 sec, what was its average acceleration
during contact?
32) A basketball is dropped to the floor from a height of 6 ft.
It rebounds to a height of 5 ft. If the ball was in contact with
the floor for 0.02 sec, what was its average acceleration during
contact?
33) A volleyball is dropped from a height of 5 ft and rebounds to
a height of 5 ft. The ball was in contact with the floor for 0.1
sec. What was its average acceleration during contact.
34) An arrow while being shot from a bow was accelerated over a
distance of 3 ft. If its speed at the moment it left the bow was
150ft/sec, what was the average acceleration imparted by the boa?
35) A baseball pitcher pitches a fastball. The ball accelerates
over a distance of 8ft. It its speed at the moment it left the
pitcher's hand was 100ft/sec, what was the average acceleration
imparted by the pitcher?
36) A golf ball is accelerated over a distance of .5 feet. If its
speed at the moment it left the golf club was 100 ft/sec, what
was the average acceleration imparted by the golf club?
37) A boy throws a ball straight up in the air and catches it (
at the same height from which he threw it) 2 sec later. How fast
was the ball moving when it left his hand? How high did the ball
rise above the point from which it was thrown?
38) A child throws a ball straight up in the air and catches it(
at the same height from which it was thrown) 3 sec later. How
fast was the ball moving when it left the child's hand? How high
did the ball rise above the point from which it was thrown?
39) A girl tosses a baseball straight up in the air and catches
it( at the same height from which she threw it) 1.5 sec later.
How fast was the ball moving when it left her hand? How high did
the ball rise above the point from which it was thrown?
40) A ball is dropped from a height of 10 ft to a flat surface
and bounces to height of 2.5 ft. What is the velocity of the ball
just before it touches the surface? How much time elapses from
the instant the ball is dropped to its arrival at the top of its
bounce? What is the velocity of the ball just after it leaves the
surface?
41) A ball is dropped to the ground from a height of 20 ft and
rebounds to a height of 16ft. What is the velocity of the ball
just before it touches the ground? How much time elapses from the
instant the ball is dropped to its arrival at the top of its
bounce? What is the velocity of the ball just after it leaves the
surface?
42) A tennis ball is dropped to the court from a height of 8 ft
and rebounds to a height of 4 ft. What is the velocity of the
ball just before it touches the ground? How much time elapses
from the instant the ball is dropped to its arrival at the top of
the its bounce? What is the velocity of the ball just after it
leaves the surface?
43) A man throws a baseball from second base to the catcher, a
distance of approximately 39 ft. What is the least speed with
which the ball must leave his hand in order to cover this
distance, arriving at the same elevation above the ground?
44) A child throws a rubber ball to a classmate, a distance of 10
ft. What is the least speed with which the ball must leave the
childs hand in order to cover this distance, arriving at the same
elevation above the ground?
45) A football player throws a ball 17 ft. What is the least
speed with which the ball must leave her hands in order to cover
this distance, arriving at the same elevation above the ground?
46) A golf ball is driven horizontally from a point which is 10
ft above the level fairway. It is strikes the ground at a point
150 yds horizontally from the start, what was the initial
velocity?
47) A child throws a ball from height of 4 ft into a basket ont
he floor 20 ft horizontally in from of the starting position.
What is the initial velocity?
48) An object is pushed off the edge of a table 2.5 ft above the
ground. It lands on the floor 10 ft horizontally in from of the
starting position. What is the initial velocity?
48) An object is pushed off the edge of a table 2.5 ft above the
ground. It lands on the floor 10ft horizontally from the table
top. What is the initial velocity of the object?
49) A juggler performs in a room whose ceiling is 4 ft above the
level of his hands. He throws a ball virtually upward so that it
just reaches the ceiling. a) with what initial velocity does he
throw the ball? b) How many seconds are required for the ball to
reach the ceiling? He throws a second ball upward with the same
initial velocity, at the instant that the first ball is at the
ceiling. c) How long after the second ball is thrown do the two
galls pass each other? d) When the balls pass each other , how
far are they above the juggler's hands?
50) 4.5 yards
51) 6 ft
52) A ball is thrown vertically upward from the ground and a
student gazing out of the window sees it moving upward past him
at 16 ft/sec. The window is 32 ft above the ground. a) How high
does the ball go above the ground? b) How long does it take to go
from a height of 32 ft to its highest point? c) Find its velocity
and acceleration .5 sec after it left the ground, and 2 sec after
it left the ground.
53) 12 ft/sec, 18 ft, 32 ft, .5 sec, 2 sec.
54) 20 ft/sec, 16 ft, 32 ft, .5 sec, 2 sec.
55) A baseball pitcher releases his fast ball with a velocity of
75 mi/hr. a) How fast is this in ft/sec? b) What is the angular
velocity of his hand at release if the effective length of his
arm is 3 ft? c) if he were to maintain this angular velocity and
twist his body so as to increases the effective length of his arm
to 4 ft, what would be the velocity of his fast ball?
56) 60 mi/hr, 4 ft, 5 ft.
57) 90 mi/hr, 3 ft, 5 ft.
58) The coefficient of restitution of a super ball on a
basketball floor is .9. a) If the ball is dropped from a height
of 20 ft, to what height will the ball rebound? b) With what
velocity will the ball contact the floor and leave the floor?
59) .5, 30 ft
60) .8, 16 ft
61)
62) In a tug of war one team is slowly giving way to the other.
What work is being done and by whom?
63) A man rowing a boat upstream is at rest with respect to the
shore. a) is he doing any work? b) If he stops rowing and moves
down with the stream, is any work being done on him?
64) In weight lifting, is power best tested by how much weight
an individual can lift in one maximal effort or by how many
repetitions an individual can do in a specified time?
65) Does the center of mass of a solid body necessarily lie
within the body? If not, give examples.
66) Can a body have energy without having momentum? Explain. Can
a body have momentum without having energy? Explain.
67) A car is traveling at 60 mi/hr. How much faster must it go in
order to double its kinetic energy?
68) 50 mi/hr
69) 55 mi/hr
70) What force acting for .001 sec, will change the velocity of a
4 oz baseball from 80 ft/sec eastward to 40 ft/sec westward?
71) .02 sec, 2 oz., 100 ft/sec, 50 ft/sec.
72) .005 sec, 8 0z, 75 ft/sec, 25 ft/sec.
73) A baseball weighing 4 oz is thrown with a velocity of 75
ft/sec. What energy does it possess due to its motion? What force
does it exert on the catcher's glove it it is stopped in a
distance of 6 in?
74) 12 oz, 45 ft/sec, 2 ft.
75) 4 oz, 80 ft/sec,18 in.
76) In the superstar competition, two teams are engaged in a tog-
o-war. The coefficient of friction for both teams it .8. One team
( A) has members weighing, 200 lbs, 250lbs, 300 lbs, 270 lbs, 240
lbs and 190 lbs. Team B has members weighing, 150 lbs, 160 lbs,
200 lbs, 230 lbs, 220 lbs, 155lbs, 185 lbs, and 200 lbs. The team
which can overcome the friction of the other team first will win.
Assuming both teams can pull equally hard, which team will win
and how much force will each of the winning team members need to
produce on the average?
77) .7, team a, 50,60,65,85,55 90. Team b, 60, 65,70,80,90,95.
78) .9, team a, 100,200,125,175,250. team b, 150,180,190,120,110.
79) A football player is pushing a blocking sled which weighs 300
lb. The coefficient of friction between the sled and the ground
is .6. If the player pushes with a 250 lb force, how fast will
the sled be going in 2 sec?
80)200 lb, .8,200 lb, 2 sec.
81) 300 lbs, .9,360 lb, 2 sec.
82) a 16 lb block is lifted vertically at a constant velocity of
10 ft/sec through a height of 20 ft. How great a force is
required? How much work is done? What becomes of the work?
83)10lb,15 ft/sec,30 ft.
84) 14 lb, 35 ft/sec,10ft.
85) What force must a man exert to hold up a wheelbarrow which,
with contents weights 100 lb? Consider distance to wheel
horizontally from handles and center of gravity as 40" and 16"
respectively.
86) 125lbs, 52", 18".
87) 150 lb, 45",24".
88) A man holds a 10 lb weight in his hand with his forearm
horizontal. Find the tension on the tendon (force) if it is one
inch in perpendicular distance from the elbow joint and if the
weight is 16 in from the elbow?
89) 12 lb,1 inch, 15 in.
90) 14 lb, 1 in, 12 inches.
91) A diver can change her moment of inertia from 6 slug-ft2
(straight) to 1 slug-ft2 ( tucked). If she leaves the board with
an angular velocity of .5 rad/sec and has 5 seconds of flight
time, how many revolutions can she complete in a straight
position? How many revolutions can she complete in a tuck
position?
92) 8 slug/ft2, ,2 slug/ft2,.6 rad/sec, 4 sec.
93) 5, 3, .6, 6
94) Compute the moment of inertia of each limb in the flexed and
extended positions and determine it's angular acceleration in
each position if exposed to a torque of 10 lb-ft.
upper arm forearm hand
arm weight 3.5 lb 2 lb .8 lb
flexed 6 in 8 in 6 in
extended 6 in 16 in 24 in
thigh leg foot
leg weight 12 lb 6 lb 2 lb
flexed 8 in 15 in 20 in
extended 8 in 28 in 40 in
r = distance from center of gravity of segment to axis of
rotation ( hip or shoulder)
'*********************************************************
Last problem set
1) A baseball pitcher pitches a softball. The initial ball
velocity is 0 m/sec. The final velocity is 30 m/sec. If the ball
is accelerated over a distance of 1 meter, what was the average
acceleration the pitcher imparted to the softball?
2) A ball is dropped from some distance. The velocity of ball
contact is 3 m/sec the rebound velocity is 2.5 m/sec. What is the
coefficient of restitution of the ball/floor interface?
3) An object is pushed off the edge of a table 2.5 meters above
the ground. It lands on the floor 10 feet horizontally from the
table top. What is the initial horizontal velocity of the object?
4)A javelin thrower releases the javelin with a velocity of 74
m/hr. How fast is this in ft/sec? What is the angular velocity of
his hand at release if the effective length of his arm is 3 ft?
5) What force, acting for .001 sec, will change the velocity of a
4 oz baseball from 80 ft/sec Northward to 40 ft/sec Southward?
6) A person is pushing a cart which weighs 200 lbs down the
hallway. The coefficient of friction between the cart and the
floor is .80. If the person pushes with a force of 200 lbs, how
fast will the sled be going in 2 sec?
7) If a 4 kg ball travels at a velocity of 4 m/sec in the
Northward direction and is hit with a 1 kg ostrich egg traveling
Northeast at a velocity or 1 m/sec, what is the momentum of the
system?
8) What is the angular acceleration of a ball if it is angularly
accelerated from 3 rad/sec to 5 rad/sec over 3 sec.
'****************************************************************
Practice Problem Set
Kinesiology 350
1) If the horizontal velocity of a ball is 3 m/sec and the
vertical velocity is 6 m/sec, what is the resultant velocity of
the ball? What is the angle of projection of the ball?
2) An object weighs 4 N and has a coefficient of friction between
itself and the ground of .8, what is the force of friction
necessary to move the object?
3) What work is performed if a 13 lb object is lifted from a
distance of 5 ft above the ground to 10 ft above the ground?
4) Which type of muscular contraction generates the largest
amount of force?
5) How much force is necessary to stop a 10 N object in 3 sec
travelling at 5 m/sec eastward?
6) With what velocity will a ball hit the ground if it is dropped
30 feet.
7) There are two balls of silly putty, Ball A and Ball B. If ball
B has a velocity of 3 m/sec southward and a mass of 4 kg and
ball A has a velocity of 4 m/sec NW and a weight of 8 N what is
the momentum and direction of the system after they collide and
stick together?
8) Is there a real life situation where a ball might rebound
higher than the point where it was last touched?
9) From what distance was the golf ball dropped if it takes 10
seconds to hit the ground.
10) From problem 9, if the ball has a mass of .2 kg what force
would it have when it reached the ground? How would the force
change if the had a parachute?
11) Car A is travelling North at a velocity of 60 m/hr and is 30
ft behind car B which is travelling North at 55 m/h. How long
will it take car A to pass car B?