Answer:
C
Explanation:
acceleration is a change in velocity which means a time rate change in velocity but velocity is the time rate change in displacement
We need optics to help aid people who have short or long sightedness.
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Answer:
<h2>3 kg </h2>
Explanation:
The mass of an object given it's force and acceleration can be found by using the formula

f is the force
a is the acceleration
From the question we have

We have the final answer as
<h3>3 kg</h3>
Hope this helps you
Answer:
To achieve the velocity of 40 m/sec height will become 4 times
Explanation:
We have given initially truck is at rest and attains a speed of 20 m/sec
Let the mass of the truck is m
At the top of the hill potential energy is mgh and kinetic energy is 
So total energy at the top of the hill 
At the bottom of the hill kinetic energy is equal to
and potential energy will be 0
So total energy at the bottom of the hill is equal to 
Form energy conservation 
, for v = 20 m/sec

Squaring both side

h = 20.408 m
Now if velocity is 0 m/sec


h = 81.63 m
So we can see that to achieve the velocity of 40 m/sec height will become 4 times