A 718 N student stands in the middle of a frozen pond having a radius of 4.7 m. He is unable to get to the other side because of a lack of friction between his shoes and the ice. To overcome this difficulty, he throws his 2.8 kg physics textbook horizontally toward the north shore at a speed of 5.5 m/s. How long does it take him to reach the south shore?
2007-12-09 08:35:35 · 2 answers · asked by Anonymous in Science & Mathematics ➔ Physics
0=m1V1 + m2V2
V2= (m1/m2)V1
t=S/V2
t= Sm2/(m1V1)
t= 4.7 x [718/9.81] /[ 2.8 x 5.5]=
t=13 sec
2007-12-09 08:39:32 · answer #1 · answered by Edward 7 · 1⤊ 1⤋
Haha, if it were me, I would have tossed my physics text book first thing too.
Anyway, back on topic:
M1V1 = M2V2 (conservation of momentum)
Letting M1V1 = mass and velocity of the book
And M2V2 = mass and velocity of the student
To get the mass of the student: 718N / 9.8m/s^2 = 73.19kg
2.8kg * 5.5m/s = 73.19kg * V
0.2104 m/s = V
To get time:
D = V t
4.7m / 0.2104m/s = t
22.34 s = t
Edit: Answer from poster above has correct formula, but he input his equation into his calculator incorrectly.
2007-12-09 08:48:56 · answer #2 · answered by Acorns 3 · 0⤊ 1⤋