Answer:
m = 2.2 x 10⁻⁴ kg = 0.22 g
Explanation:
The surface tension of water is 0.072 N/m. So in order for the bug to avoid sinking, its weight per unit length of contact must be no more than the surface tension of water. Therefore,
where,
m = mass of bug = ?
g = acceleration due to gravity = 9.81 m/s²
L = Contact length = (contact length of each leg)(No. of Legs) = (5 mm)(6)
L = 30 mm = 0.03 m
Therefore,
<u>m = 2.2 x 10⁻⁴ kg = 0.22 g</u>
Answer:
1.65
Explanation:
The equation of the forces along the horizontal direction is:
(1)
where
F = 65 N is the force applied with the push
is the frictional force
m = 4 kg is the mass
is the acceleration
The force of friction can be written as (2), where
is the coefficient of kinetic friction
R is the normal force exerted by the floor
The equation of forces along the vertical direction is
(3)
since the bookcase is in equilibrium. Substituting (2) and (3) into (1), we find
And solving for ,
Answer:
Counterclockwise
Explanation:
We need to calculate the clocwkise and the counterclockwise torque.
The clockwise torque is the one generated by the child sitting on the right. This torque is given by:
where
is the force exerted by the child (his weight)
d = 1.8 m is the distance from the pivot point
So, the clockwise torque is
The counterclockwise torque is the one generated by the adult pushing on the left, and it is given by
where
F = 151 N is the force applied
d = 3.0 m is the distance from the pivot
Substituting,
So, the net torque is
And since the counterclockwise momentum is greater than the clockwise one, the teeter-totter will rotate counterclockwise.