4. A student throws a set of keys vertically upward to her sorority sister, who is in a window 4.00 m above. The second student catches the keys 1.50 s later. (a) With what initial velocity were the keys thrown? (b) What was the velocity of the keys just before they were caught?

Question

Physics

Sullivan Watkins

17 February, 22:58

4. A student throws a set of keys vertically upward to her sorority sister, who is in a window 4.00 m above. The second student catches the keys 1.50 s later. (a) With what initial velocity were the keys thrown? (b) What was the velocity of the keys just before they were caught?

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Answers (1)

Know the Answer?

Derrick Shields · Answer 1

a) 10.0 m/s

b) - 4.68 m/s

Explanation:

Given:

y₀ = 0 m

y = 4.00 m

t = 1.50 s

a = - 9.8 m/s²

Find: v₀, v

y = y₀ + v₀ t + ½ at²

4.00 = 0 + v₀ (1.50) + ½ (-9.8) (1.50) ²

v₀ = 10.0 m/s

v = at + v₀

v = (-9.8) (1.50) + 10.0

v = - 4.68 m/s