Question

22. Kerry Klutz drops her physics book off her aunt’s high rise balcony. It hits the ground below 1.5 s later.

a. With what speed does it hit?
b. How high is the balcony (ignore air drag).

Answer 1

a). Gravity makes falling objects fall 9.8 m/s faster every second.
After 1.5 seconds, it's falling at (1.5 x 9.8) = 14.7 m/s .

b). The average speed of the physics book is (1/2) (0 + 14.7) = 7.35 m/s .

Falling at an average speed of 7.35 m/s for 1.5 seconds,
the book falls

(1.5 x 7.35) = 11.025 meters

Answer 2

Part (a) v = 14.7 m/s

Part (b) h = 11.025 m

Step-by-step explanation:

Part (i)

As we know that book is moving under constant acceleration which is due to gravity

so here we know that

`a = 9.8 m/s^2`

`\Delta t = 1.5 s`

`v_i = 0`

so here we will have

`v_f = v_i + at`

`v_f = 0 + (9.8)(1.5)`

`v_f = 14.7 m/s`

Part (b)

height of balcony can be found by another kinematics equation

`\Delta y = v_i t + (1)/(2)at^2`

`\Delta y = 0 + \{1}{2}(9.8)(1.5)^2`

`\Delta y = 11.025 m`