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PROBLEM 11.140
A motorist starts from rest at Point A on a circular entrance ramp
when t 0, increases the speed of her automobile at a constant
rate and enters the highway at Point B. Knowing that her speed
continues to increase at the same rate until it reaches 100 km/h
at Point C, determine (a) the speed at Point B, (b) the
magnitude of the total acceleration when t 20 s.
PROBLEM 11.141
Racecar A is traveling on a straight portion of the track while
racecar B is traveling on a circular portion of the track. At the
instant shown, the speed of A is increasing at the rate of 10
m/s
2
, and the speed of B is decreasing at the rate of 6 m/s
2
. For
the position shown, determine (a) the velocity of B relative to
A, (b) the acceleration of B relative to A.
PROBLEM 11.142
At a given instant in an airplane race, airplane A is flying
horizontally in a straight line, and its speed is being increased
at the rate of
2
8 m/s .
Airplane B is flying at the same altitude
as airplane A and, as it rounds a pylon, is following a circular
path of 300-m radius. Knowing that at the given instant the
speed of B is being decreased at the rate of 2
3 m/s ,
determine,
for the positions shown, (a) the velocity of B relative to A,
(b) the acceleration of B relative to A.
PROBLEM 11.143
A race car enters the circular portion of a track that has a radius
of 70 m. When the car enters the curve at point P, it is
travelling with a speed of 120 km/h that is increasing at 5 m/s
2
.
Three seconds later, determine (a) the total acceleration of the
car in xy components, (b) the linear velocity of the car in xy
components.
y
PROBLEM 11.144
An airplane flying at a constant speed of 240 m/s makes a banked horizontal turn.
What is the minimum allowable radius of the turn if the structural specifications
require that the acceleration of the airplane shall never exceed 4g?
PROBLEM 11.145
A golfer hits a golf ball from Point A with an initial velocity of 50 m/s at an angle
of 25° with the horizontal. Determine the radius of curvature of the trajectory
described by the ball (a) at Point A, (b) at the highest point of the trajectory.
PROBLEM 11.146
Three children are throwing
snowballs at each other. Child A
throws a snowball with a horizontal
velocity v0. If the snowball just
passes over the head of child B and
hits child C, determine the radius of
curvature of the trajectory
described by the snowball (a) at
Point B, (b) at Point C.
PROBLEM 11.146 (Continued)
PROBLEM 11.147
Coal is discharged from the tailgate A of a dump truck with an
initial velocity 2 m/s
Av50. Determine the radius of
curvature of the trajectory described by the coal (a) at Point A,
(b) at the point of the trajectory 1 m below Point A.
PROBLEM 11.148
From measurements of a photograph, it has been found that as the
stream of water shown left the nozzle at A, it had a radius of
curvature of 25 m. Determine (a) the initial velocity
v
A
of the
stream, (b) the radius of curvature of the stream as it reaches its
maximum height at B.
