I feel like the answer would be B. The chair pushes down on the floor becuase the question says when you sit in a chair, your body exerts a downward force on the chair so it would be pushing downward meaning that the chair would also go down making it push onto the floor.
Potential energy
potential energy is the stored energy an object has, the bike is not moving and it just sitting on the hill, with the stored energy
Explanation:
It is given that,
Speed of the jet airplane with respect to air, 
If the wind at the airliner’s cruise altitude is blowing at 100 km/h from west to east, 
(A) Let 
is the speed of the airliner relative to the ground if the airplane is flying from west to east,
(B) Let 
is the speed of the airliner relative to the ground if the airplane is flying from east to west,
Hence, this is the required solution.
Answer:
B) Gets smaller
Explanation:
The difference of phase between current and voltage in a AC circuit is the phase angle and it depends on the value of Z ( circuit impedance)
Z = R + X where R is the resistive component and X the reactance component, which is due either to a presence of an inductor or a capacitor. In any case the total impedance depends on R the resistive, and the phase angle φ is:
tan⁻¹ φ = X/R
Have a look to a pure capactive circuit (we are talking about AC current) in this case current leads voltage by 90⁰. If we add a resistor in the circuit the current still will lead a voltage but in this condition the phase angle will be smaller,
If R increase, X/R decrease and tan⁻¹ φ also decrease
