Calculus: I need help please!

Calculus: I need help please!

I would really, really appreciate answers. Out of the many assignment questions, my friends and I do not even know how to start these ones, and our tutor was no help and nor was google. Please help us! 

RELATES RATES QUESTION: A horizontal eaves trough 2m long has ends in the shape of isosceles triangles that are 10 m across the top and 10 cm deep. During a rainstorm, leaves plug up the trough and the water in the trough is rising at a rate of 1.5 cm/min. when the depth is 4 cm, how fast is the volume of water in the trough increasing at that moment? 

Question 2: A stone is launched vertically upward from a cliff 192 ft above the ground at a speed of 64 ft/s. Its height above the ground t seconds after the launch is given by s = -16t2 + 64t + 192 for 0 < t < 6. What is the velocity of the stone when it first reaches a height of 48 ft above the cliff? 

Question 3: linearization, photo attached!!

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