21) Acceleration from D to E: 
22) The acceleration of the bus from D to E is 
Explanation:
21)
The acceleration of an object is equal to the rate of change of velocity of the object. Mathematically:

where
u is the initial velocity
v is the final velocity
t is the time elapsed
In this problem, we want to measure the acceleration of the bus from point D to point E. We have:
- Initial velocity at point D: u = 0
- Final velocity at point E: v = 5 m/s
- Time elapsed from D to E: t = 21 - 16 = 5 s
Therefore, the acceleration between D and E is

22) This question is the same as 21), so the result is the same.
Learn more about acceleration:
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Air pressure decreases as altitude increases. this is because air pressure is caused by the gravity of earth, the gravity pulls on the air, compacting it and making a pressure.
But as we go higher, gravity decreases, causing less pull on the air resulting in less air pressure.<span />
Explanation:
I think for anyone to answer this we need more info on what you want answered. The Sentence Itself doesn't Make Since To Me
I believe the answer is the fourth one, hope this helps
Answer:
- A book lying on a table - Balanced force
- An airplane cruising in level flight - Balanced
- A rock falling from a cliff - Unbalanced force
- A bridge collapsing in an earthquake - Unbalanced force
- A man sitting on a park bench - Balanced force
- A space shuttle taking off - Unbalanced force
- A car maintaining a constant speed on a straight road - Balanced force
- An airplane landing - Unbalanced force
Explanation:
Usually, one or more forces act on a body at an instant of time. When these forces acting on a body and bring the body in the equilibrium position, the force is said to be balanced. The unbalanced force changes the equilibrium state of the body.
As in the case of an airplane cruising in a level flight, the weight of the plane will be equal to the lift force and the thrust is equal to the drag. So the plane is experiencing a balanced force.