Math 142 Test1 S22
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Test 2
1 (a) (7 points) For + 66 = 0 , show that if = ,then p is constant along (t) .
Explain why z(t) is a straight line.
b) (7 pints) suppose instead that t + =
a(t) with = , given ( 0 )=0 ,p(o0)
rt-plane.
10 , with u ()= 30 . 1p. solve for
= 100 . sketch the solutions in the
2 · (a) (8 points) prove that if C is constant , then all solutions to + cdd = 0 are of the
form p(r , t) = f( ct) , where f() =p( 0) .
(b) (4 points) suppose u() = 60 - 4p, and p(,0) = 5 +1(2+ ) · Find an approxi-
mate solution p(w t) .
(c) (4 points) sketch p( 0) ,p(r , 1) , and p(r , 2) , from your approximation above.
5
2
U() = 75 32 .
(a) (10 points) solve for p(,t) in all regions of the (w , t) -plane.
(b) (4 points) sketch the characteristics in all regions of the (w , t) -plane.
(c) (4 points) sketch a graph of p(r , 1) .
(d) (10 points) solve for the path of a car (t) in this situation, if r() = 0 .
Test 3
(g0)= 1 +2 0< <3
7 ≥ 3
u( )=10 ·
(a) (6 points) Find where a shock occurs and the exact line of the shock.
(b) (10 points) solve for p(r , t) in all regions of the (w , t) -plane.
(c) (5 points) sketch the characteristics in the t-plane.
(d) (3 points) sketch p( · 1) .
(e) (3 points) sketch p(r , . 5) .
5 suppose pt + 6p = 0 , U ()= 50 . 25p, and
1 p( 0)
1 1 2 3 4 5
A Shock will form along a characteristic from
to (S ts) in the
(r , t) plane.
(a) (9 points) Find *
(b) (3 points) Find ts
(c) (3 points) Find s ·
2023-07-28