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A student throws a set of keys vertically upward to his fraternitybrother, who i

ID: 1735137 • Letter: A

Question

A student throws a set of keys vertically upward to his fraternitybrother, who is in a window 4.05 mabove. The brother's outstretched hand catches the keys1.30 s later. (a) With what initial velocity were the keysthrown?
1 m/s

(b) What was the velocity of the keys just before they were caught?(Take upward as the positive direction.)
2 m/s (a) With what initial velocity were the keysthrown?
1 m/s

(b) What was the velocity of the keys just before they were caught?(Take upward as the positive direction.)
2 m/s

Explanation / Answer

use: .     height = v t - (1/2) g t2 .      4.05 = v * 1.30 - (1/2) * 9.8 * 1.302 .         v =   9.485m/s . Use... .      final velocity = initialvelocity   - g t .                        =    9.485 -   9.8 * 1.3  =    -3.255 m/s .         v =   9.485m/s . Use... .      final velocity = initialvelocity   - g t .                        =    9.485 -   9.8 * 1.3  =    -3.255 m/s