Answer:t=0.81 s
Explanation:
Given
Penguin slides down with constant velocity of 3.57 m/s
as the Penguin Slides with constant velocity therefore 
is zero on Penguin
friction Force
coefficient of Kinetic friction
after reaching on floor final velocity of penguin will be zero after time t
thus
here 
(deceleration)
Salt is a substance because a substance is a material that has constant composition regardless of its source. Salt is the only option that matches this description
In order to make things easier to describe and explain, let's call
the resistance of each bulb 'R', and the battery voltage 'V'.
a). In series, the total resistance is 3R.
In parallel, the total resistance is R/3.
Changing from series to parallel, the total resistance of the circuit
decreases to 1/9 of its original value.
b). In series, the total current is V / (3R) .
In parallel, the total current is 3V / R .
Changing from series to parallel, the total current in the circuit
increases to 9 times its original value.
c). In series, the power dissipated by the circuit is
(V) · V/3R = V² / 3R .
In parallel, the power dissipated by the circuit is
(V) · 3V/R = 3V² / R .
Changing from series to parallel, the power dissipated by
the circuit (also the power delivered by the battery) increases
to 9 times its original value.
For the First answer, It would be "A"
The for the next one the answer is "C"
I hope this helps. :)
