Question

A 760 N man stands in the middle of a frozen pond of radius 6.0 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 1.2 kg physics textbook horizontally toward the north shore, at a speed of 6.0 m/s. How long does it take him to reach the south shore?

Answer 1

Answer:

Explanation:

Given

weight of man $W=760 N$

mass of man $m_1=\frac{760}{g}=76\ kg$

radius of pond $r=6\ m$

mass of textbook $m_2=1.2\ kg$

speed of text book $v_2=6\ m/s$

Let speed at which man recoils is $v_1$

Initially momentum is zero as man is at rest

Conserving momentum

$0=m_1v_1+m_2v_2$

$0=76\times v_1+1.2\times 6$

$v_1=-0.1\ m/s$

i.e. 0.1 m/s towards south

time taken to reach other side in absence of friction is given by

$t=\frac{distance}{speed}$

$t=\frac{6}{0.1}$

$t=60 s\approx 1\ minute$