Answer:
A chemical change produces a new substance, while a physical change does not
Answer:
0.50m/s
Explanation:
Average velocity is the change in displacement of a body with respect to time.
Velocity = ∆S/∆t
∆S = 100m - 70m
∆S = 30m
∆t = 2min - 1 min
∆t = 1min = 60secs
Substitute the given parameters into the formula for velocity
Velocity = 30m/60s
Velocity = 1/2 m/s
Average Velocity = 0.5m/s
Answer:
588 J
Explanation:
PE (potential energy) = (mass) x (gravity) x (height)
mass = 12 kg
gravity = 9.8m/s^2
height = 5 m
PE = (12) x (9.8) x (5) = 588 J (Joules)
Answer is D - from the equation of electric field for point charge
Answer:
B
Volume decreases due to less molecular motion of the gas inside the football.
Explanation:
Assuming that the atmospheric pressure (and therefore, the pressure of the air inside the football) remains constant, this means that we can apply Charle's law, which states that:
"For a fixed amount of gas kept at constant pressure, the volume of the gas is proportional to its absolute temperature"
Mathematically:

where
V is the volume of the gas
T is its absolute temperature
In the winter month, the air becomes colder, which means that the temperature of the air (and of the gas inside the football) decreases. As the average kinetic energy of the molecules of a gas is proportional to its absolute temperature, this also means that there will be less molecular motion in the gas, and therefore (as stated by Charle's law) the volume of the gas also decreases.