Explanation:
This is because the drag force suffered by the aircraft is proportional to the speed at which it travels. The thrust of the engines prints a speed to the plane and this speed prints a drag force, always reaching an equilibrium point of these two forces where the speed of the plane is constant and the acceleration is equal to zero.
Therefore, by reducing the thrust, the drag force is greater and the plane begins to decrease its speed, until it reaches the point where the new drag force is matched with the new thrust force, giving it a new final speed , without acceleration.
Answer:
p to the left
Explanation:
According to law of conservation of momentum "total momentum of an isolated system remains constant".
we consider astronaut and astronaut drill as an isolated system. If the drill gain momentum p to the right so in order for momentum to remain constant the astronaut will gain the same momentum but in opposite direction i.e momentum p to the left.
Initial momentum = 0 ( before she throw astronaut belt)
Final momentum = p - p = 0 (After she throw astronaut belt)
Hence momentum of the system remains constant i.e zero.
Answer:
The correct option is 'd': The change in shape of an object.
Explanation:
Since by definition physical change is defined as a change that changes only the form of an object or substance and producing no change in the chemical composition of the substance. Physical changes are reversible in nature.
As we can see from all the options the change in the shape of the object is a reversible change as we can always remold any substance in any shape, thus it confirms to a physical change.
The change in the molecular composition of an object is a hallmark of a chemical reaction thus indicates a chemical change.
The smell change in an object is an indication of a chemical change in the object hence is not a physical change.
Answer:
Explanation:
As given, the student has three balloons and rubs two of them on a piece of wool. The rubbing of balloon on wool is the independent variable as it was done on two and not on the third as control.
V = t^2 - 9t + 18
position, s
s = t^3 /3 - 4.5t^2 +18t + C
t = 0, s = 1 => 1=C => s = t^3/3 -4.5t^2 + 18t + 1
Average velocity: distance / time
distance: t = 8 => s = 8^3 / 3 - 4.5 (8)^2 + 18(8) + 1 = 27.67 m
Average velocity = 27.67 / 8 = 3.46 m/s
t = 5 s
v = t^2 - 9t + 18 = 5^2 - 9(5) + 18 = -2 m/s
speed = |-2| m/s = 2 m/s
Moving right
V > 0 => t^2 - 9t + 18 > 0
(t - 6)(t - 3) > 0
=> t > 6 and t > 3 => t > 6 s => Interval (6,8)
=> t < 6 and t <3 => t <3 s => interval (0,3)
Going faster and slowing dowm
acceleration, a = v' = 2t - 9
a > 0 => 2t - 9 > 0 => 2t > 9 => t > 4.5 s
Then, going faster in the interval (4.5 , 8) and slowing down in (0, 4.5)
