Question

You drop a 3.00 kg book to a friend who stands on the ground at distance D = 13.0 m below. Your friend's outstretched hands are at distance d = 1.60 m above the ground (see the figure). (a) What is the speed of the book when it reaches her hands? (b) If we substituted a second book with twice the mass, what would its speed be when it reaches her hands? (c) If, instead, the book were thrown down with initial speed 6.50 m/s, what would be the answer to (a)?

Answer 1

to solve this trouble. we use the kinematics formulas (are 3)

a) for to know the velocity (vf) we can use the second or the third formula, how we know the distance (D-d) we opt to use the third formula

how the book was dropped, his initial velocity is equal to zero

the acceleration is due to gravity. and the distance is the difference between the distance to the ground and the distance to the hands

b) the same, because the mass do not participate in the acceleration

c) if the initial velocity is Vo=6.5m/s the formula would be