(C) In case 1 it says the KE is positive but the total energy is negative. How i

Question

(C) In case 1 it says the KE is positive but the total energy is negative. How is this possible? Explain what it means for the total energy to be negative.

(D) In case 3, the total energy is 200 J. How fast is the bulldog when he passes the bottom of the well? _______ meters/second. Explain.

In the three figures labeled A, B and C below are shown three situations in which a bulldog on a skateboard traverses a dip in the ground. (The dips are all the same.) In A, the bulldog enters the dip traveling at a non-0 kinetic energy (KE). In B, when he leaves the dip, he has 0 KE. In C, he begins in the dip (at the position indicated) at a KE of 0. Since he is riding a skateboard, friction may be ignored. Take g 10 N/kg. --KE > 0 here "Oat thi tted KE = 0 here O at this dotted line KE 0 here 0 at this-dotted tted line

Explanation / Answer

Given are

M=20kg

K.E=380J

H=?

G=10

In this the gravitational potential energy is converted to kinetic energy so we can say

K.E=P.E

380=mgh

380/20*10=h

1.9m=h—answer a

b)total energy at the top is mgh

=1.9mg

=1.9*20*10

=380J

It will be same not negative

c)E=200J

v=?

m=20kg

same as we did in part 1

In this the gravitational potential energy(at the top it is the total energy) is converted to kinetic energy so we can say

K.E=P.E

1/2mv^2=mgh

1/2mv^2=200

V^2=200*2/20

V=20m/sec--answer

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