If the acceleration is constant (negative or positive) the instantaneous acceleration cannot be
Average acceleration: [final velocity - initial velocity ] /Δ time
Instantaneous acceleration = d V / dt =slope of the velocity vs t graph
If acceleration is increasing, the slope of the curve at one moment will be higher than the average acceleration.
If acceleration is decreasing, the slope of the curve at one moment will be lower than the average acceleration.
If acceleration is constant, the acceleration at any moment is the same, then only at constant accelerations, the instantaneuos acceleration is the same than the average acceleration.
Constant zero acceleration is a particular case of constant acceleration, so at constant zero acceleration the instantaneous accelerations is the same than the average acceleration: zero. But, it is not true that only at zero acceleration the instantaneous acceleration is equal than the average acceleration.
That is why the only true option and the answer is the option D. only at constant accelerations.
the answer is D) The air in the aquarium is saturated
none of the other answers were realistic AND I took this before so I know the right answer.
as per the question charlie runs to the store which is 4 km away
hence the total distance covered [S] is 4 km
he takes 30 minutes to reach the store.
hence the total time taken [t] = 30 minutes=0.5 hour
We have to calculate the average speed.
the average speed[v]= 
=
=8 km/hour
then we have to calculate the total distance traveled by charlie in 1 hour.
the distance covered S= 
=8 km/hour ×1 hour
=8 km
Hence the average speed of charlie is 8 km/hour and he covers a distance of 8 km in 1 hour.
Answer: Gravitational potential energy changes.
Explanation: This is because depending on the amount of mass in an object that’s the amount of gravity pulling you down to the center of the earth
Given
Car 1
m1 = 1300 kg
v1 = 20 m/s
m2 = 900 kg
v2 = -15 m/s
(Negative sign shows that direction of car 2 is opposite to car 1)
Procedure
As per the conservation of linear momentum, "The total momentum of the system before the collision must be equal to the total momentum after the collision". And this applies to the perfectly inelastic collision as well. Then the expression is,
Thus, we can conclude that the speed and direction of the cars after the impact is 5.68 m/s towards the first car.
