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Suppose a rocket-propelled motorcycle is fi red from rest horizontally across a canyon 1.00 km wide. (a) What minimum

constant acceleration in the x-direction must be provided by the engines so the cycle crosses safely if the
opposite side is 0.750 km lower than the starting point? (b) At what speed does the motorcycle land if it maintains
this constant horizontal component of acceleration? Neglect air drag, but remember that gravity is still acting in the
negative y-direction.

2 Answers

4 votes

Answer:

Step-by-step explanation:

I apologize for any plagiarism in my previous answer. Here is a new answer to the question:

(a) The motorcycle needs to cross the canyon safely by landing on the opposite side. Let's call the starting point of the motorcycle as point A and the landing point as point B. The horizontal distance between A and B is 1.00 km, and the vertical distance between them is 0.750 km.

To find the minimum constant acceleration in the x-direction required to cross the canyon safely, we can use the kinematic equation:

d = (1/2)at^2

where d is the horizontal distance between A and B, a is the constant acceleration in the x-direction, and t is the time it takes to cross the canyon.

We also know that the motorcycle is affected by gravity, which causes it to accelerate downwards with an acceleration of g = 9.81 m/s^2.

To cross the canyon safely, the motorcycle needs to land on the opposite side, so we can use the following inequality:

h <= (1/2)gt^2

where h is the vertical distance between A and B.

Substituting the given values, we have:

d = 1.00 km = 1000 m

h = 0.750 km = 750 m

Using the above equations, we can solve for the minimum acceleration required:

750 m <= (1/2) * 9.81 m/s^2 * t^2

1000 m = (1/2) * a * t^2

Solving for t in the first equation, we get:

t = sqrt((2 * h) / g) = sqrt((2 * 750 m) / 9.81 m/s^2) = 12.19 s

Substituting this value of t into the second equation, we get:

a = (2 * d) / t^2 = (2 * 1000 m) / (12.19 s)^2 = 6.96 m/s^2

Therefore, the minimum constant acceleration in the x-direction required to cross the canyon safely is 6.96 m/s^2.

(b) To find the speed at which the motorcycle lands, we can use the equation:

v_f = at

where v_f is the final velocity in the x-direction.

Substituting the given values, we get:

a = 6.96 m/s^2

t = 12.19 s

Therefore, the final velocity of the motorcycle in the x-direction is:

v_f = 6.96 m/s^2 * 12.19 s = 84.85 m/s

Therefore, the motorcycle lands with a horizontal speed of 84.85 m/s.

User Dinesh Shingadiya
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8.0k points
5 votes

Step-by-step explanation:

Vertical distance (note conversion to METERS from km for parameters in Q)

750 m = 1/2 at^2 Where a = 9.81 m/s^2

then t = 12.365 s

Then horizontal distance that must occur in this time frame:

1000 m = do + vot + 1/2 a t^2 ( do and vo = 0 )

where THIS a is the HORIZONTAL accel we are looking for

1000 = 1/2 a t^2

2000 = a ( 12.365)^2

a = ~ 13.1 m/s^2

User Elric
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8.0k points