I need help with the following problems: QUESTION #1 You are driving at a steady

Question

I need help with the following problems:

QUESTION #1

You are driving at a steady 10 m/s for 10 seconds, then you accelerate at 3 m/sec^2 for 5 seconds. How far have you traveled during the 15 seconds that elapsed?

QUESTION #2

A ball is thrown straight upward at time t = 0 secs, from a point on a roof 90 m above the ground. The ball rises, then falls and strikes the ground (as you would expect). The initial velocity of the ball is 54.4 m/s. What is the velocity of the ball when it is 57 m above the ground? Assume no air resistance.

Explanation / Answer

1)
d = d1 + d2

= u*t1 + u*t2 + 0.5*a*t2^2

= 10*10 + 10*5 + 0.5*3*5^2

= 187.5 m

2)

Apply, vy^2 -voy^2 = 2*a*s

vy^2 = voy^2 - 2*a*s

vy^2 = voy^2 + 2*g*y

vy = sqrt(voy^2 + 2*g*y)

= sqrt(54.4^2 + 2*9.8*(90-57))

= 60.05 m/s

= -60.05 m/s

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