Question

Cousin Milty, aged 93 and of mass 70.0 kg, pulls a 40.0 kg carton of books along his livingroom floor. Consider a period of time during which he pulls the carton at a constant speed of 0.500 m/s, through a distance of 4.00 m along a straight line, while applying a constant force of 200 N directed 30 degrees above the horizontal. Calculate:(a) The work done on the carton by Cousin Milty equals(b) The work done on the carton by the floor’s normal contact force(c) The work done on the carton by the force of gravity

Answer 1

Answer:

a) $W=692.82\ J$

b) 0

c) 0

Explanation:

Given:

mass of person, $m=70\ kg$

mass of books , $m_b=40\ kg$

velocity of pulling the books, $v=0.5\ m.s^{-1}$

distance through which the carton of books is pulled, $s=4\ m$

force applied for pulling, $F=200\ N$

direction of force above the horizontal, $\theta=30^{\circ}$

a)

Now the work done on the carton of books:

$W=F.s\cos\theta$

$W=200\times 4\times \cos30^{\circ}$

$W=692.82\ J$

b)

Since there is no vertical displacement in the carton in vertical direction along which a component of force act, so the work done due to the normal contact force is zero.

c)

Since there is no vertical motion in the carton so the work done will be zero.