Question

At time t = 0, apple 1 is dropped from a bridge onto a roadway beneath the bridge; somewhat later, apple 2 is thrown down from the same height. Figure below gives the vertical position, y of the apples versus t, time of the falling, until both apples have hit the roadway. The scaling is set by $t_s$= 2.0 s. With approximately what speed was apple 2 thrown down?

• A. 15 m/s
• B. 20 m/s
• C. 25 m/s
• D. 10 m/s

Answer 1

The correct option is A

15 m/s

$s=ut+\frac{1}{2}a{t}^2$

$s=\frac{1}{2}\times (-10)(2{)}^2=-20$

So height of building = 20m

Second time the apple takes only half the time i.e., 1 sec

So

$-20=u\left(1\right)+\frac{1}{2}(-10)(1{)}^2$

$-20=u-5$

$u=-15m/s$

The apple is thrown with velocity = 15m/s