Henrietta is going off to her physics class, jogging down the sidewalk at a speed of 2.55 m/s. Her husband Bruce suddenly realizes that she left in such a hurry that she forgot her lunch of bagels, so he runs to the window of their apartment, which is a height 35.4 m above the street level and directly above the sidewalk, to throw them to her. Bruce throws them horizontally at a time 7.00 s after Henrietta has passed below the window, and she catches them on the run. You can ignore air resistance.

Wit what initial speed must Bruce throw the bagels so Henrietta can catch them just before they hit the ground? Where is Henrietta when she catches the bagels?

Question

Rebecca Phillips

Physics

15 January, 08:02

Henrietta is going off to her physics class, jogging down the sidewalk at a speed of 2.55 m/s. Her husband Bruce suddenly realizes that she left in such a hurry that she forgot her lunch of bagels, so he runs to the window of their apartment, which is a height 35.4 m above the street level and directly above the sidewalk, to throw them to her. Bruce throws them horizontally at a time 7.00 s after Henrietta has passed below the window, and she catches them on the run. You can ignore air resistance.

Wit what initial speed must Bruce throw the bagels so Henrietta can catch them just before they hit the ground? Where is Henrietta when she catches the bagels?

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Answers (1)

Know the Answer?

Carsen Stein · Answer 1

u = 9.2 m/s

Explanation:

Second equation of motion:

s = u t + 0.5 a t²

The time in which book would fall 35.4 m downwards is:

Initial velocity is zero in vertical direction.

35.4 = 0 + 0.5 (9.8) t²

⇒ t² = 7.22 ⇒t = 2.68 s

The horizontal distance covered by Henrietta in (7.00 s + 2.68 s):

x = 2.55 m/s * 9.68 s = 24.684 m

The initial velocity with which the book must be thrown in order for Henrietta to catch.

24.684 m = u (2.68 s)

u = 9.2 m/s