Motion in Two or Three Dimensions

Question

A physics book slides off a horizontal table top with a speed of 1.20  . It strikes the floor after a time of 0.360  . Ignore air resistance.

Find the height of the table top above the floor. Take free fall acceleration to be g = 9.80 m/s2 .

Find the horizontal distance from the edge of the table to the point where the book strikes the floor.

Find the horizontal component of the book's velocity just before the book reaches the floor.

Find the vertical component of the book's velocity just before the book reaches the floor.

Find the magnitude of the book's velocity just before the book reaches the floor.

Find the direction of the book's velocity just before the book reaches the floor.

Answer 1

Hello Angie

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Here is the answer

Given Horizontal speed = 1.20 m/s

Time for vertical fall = 0.360 s =t

For free fall initial vertical speed = 0 m/s

Horizontal speed will remain same all along motion till book hits the ground

Using

S = ut +1/2 gt² where u = 0, S = H = ?

H= 1/2*9.8*0. 36*0.36= 0.635 m = Height of tablet

Horizontal speed at the the time of touching the ground remains the same =1.20m/s

Vertical speed at the end can be found by using

V= gt = 9.8*1.2 = 11.76 m/s

Magnitude of velocity at the time of hitting the ground =√ (1.2² + 11.76² )

Direction at the time of hitting the ground is given by

tanθ= 11.76/1.2