Since the basketball and the tennis ball both travel to the same direction relative to the ground, the velocity of the basketball relative to the tennis ball is therefore the difference of their velocities.
0.5 m/s - 0.25 m/s = 0.25 m/s
Thus, the basketball travel for 0.25 m/s relative to the tennis ball.
-- If the system is 'closed', then nothing ... including energy ... can get in or out, and the total energy inside has to be constant.
If half of the energy in the system starts out as potential energy and the rest starts out as kinetic, and then the potential energy increases, there's only one place the increase could have come from ... it could only have been converted from kinetic energy. So the <em>kinetic energy</em> in the system <em>must</em> <em>decrease</em>.
In fact, this isn't even a "result". The kinetic energy has to decrease <em><u>before</u></em> the potential energy can increase, because that's where the increase has to come from.
If the system is 'open', then energy can come in and go out. If the potential energy inside suddenly increases, we don't know where it came from, so we can't say anything about what happens to the system.
I would say C i'm not 100% sure
(a) 328.6 kg m/s
The linear impulse experienced by the passenger in the car is equal to the change in momentum of the passenger:

where
m = 62.0 kg is the mass of the passenger
is the change in velocity of the car (and the passenger), which is

So, the linear impulse experienced by the passenger is

(b) 404.7 N
The linear impulse experienced by the passenger is also equal to the product between the average force and the time interval:

where in this case
is the linear impulse
is the time during which the force is applied
Solving the equation for F, we find the magnitude of the average force experienced by the passenger:

Answer:
108.37°C
Explanation:
P₁ = Initial pressure = 101 kPa
V₁ = Initial volume = 530 m³
T₁ = Initial temperature = 10°C = 10+273.15 =283.15 K
P₂ = Final pressure = 101 kPa (because it is open to atmosphere)
V₂ = Final volume = 530 m³
P₁V₁ = n₁RT₁
⇒101×530 = n₁RT₁
⇒53530 J = n₁RT₁
P₂V₂ = n₂RT₂
⇒53530 J = n₂RT₂

Dividing the first two equations we get

∴Temperature must the air in the balloon be warmed before the balloon will lift off is 381.25-273.15 = 108.37°C