Please answer all four questions tal track. A roller-coaster car is moving at a

Question

Please answer all four questions tal track. A roller-coaster car is moving at a speed of: v = 45 ms, along a straight horizon Ignoring friction, what will its speed be after climbing the h = 25 m hill shown below? 4 " ae) +39.2 m/s bd) +20.0 m/s ac) -20.0 m/s cd) +10.8 m/s de) +7.6 m/s 5. Which one of the following statements is true? Statements concern the two "gravitational constants". Newton's universal gravitational constant, G, & the magnitude of the acceleration due to gravity, g a) The value of G is the same everywhere in the universe, but the value of g is not. b) The value of g is the same everywhere in the universe, but the value of G is not c) The values of g& G do not depend on location. d) The values of g &G; depend on location. e) The values of g& G are equal on the surface of any planet, but vary from planet to planet 6. A woman stands on the edge of a 9 m cliff& throws a 25 kg stone vertically downward with an initial speed of 20 m's for a total mechanical energy at impact of 72 J. If she were to throw the stone horizontally outward from the cliff with the same initial speed of 20 m/s, how much kinetic energy would it have just before it hits the ground? a) 88J b) 180J c) 288 J d) 72J e) 200 J rest or if in motion to remain in motion at a constant speed along a straight line? ab) velocity ac) force ce) acceleration be) equilibrium bd) inertia 7. Which one of the following terms is used to indicate the natural tendency of an object to remain at

Explanation / Answer

4). this is a conservation of energy problem

kinetic +potential at start = kinetic +potential at top

let's call the level of the horizontal track our reference level, so there is no PE there, so we have

1/2 m v^2 (level track) = 1/2 mv^2(at top) + mgh where h=25m

sub values and divide through by m:

1/2 (45m/s)^2 = 1/2 v^2 + 9.8m/s/s x 25m

solve for v: v=39.18m/s

5). part a... the value of G is same everywhere, but value of g changes.

6) 1/2*m*(vf)^2=1/2*mv^2+mgh=1/2*(0.25*20*20)+0.25*9.8*9=75 J

7) part d.. inertia

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