She does 200J .
We know she uses 20N of force and 10m is the distance. We multiply both numbers and we are given our answer of 200J. Hope this was helpful. :)
Answer:
KE₂ = 6000 J
Explanation:
Given that
Potential energy at top U₁= 7000 J
Potential energy at bottom U₂= 1000 J
The kinetic energy at top ,KE₁= 0 J
Lets take kinetic energy at bottom level = KE₂
Now from energy conservation
U₁+ KE₁= U₂+ KE₂
Now by putting the values
U₁+ KE₁= U₂+ KE₂
7000+ 0 = 1000+ KE₂
KE₂ = 7000 - 1000 J
KE₂ = 6000 J
Therefore the kinetic energy at bottom is 6000 J.
Answer:
Option 3. The tennis ball began from rest and rolls at a rate of 14.7 m/s safer 1.5 seconds.
Explanation:
To know the the correct answer to the question, it is important that we know the definition of acceleration.
Acceleration can simply be defined as the rate of change of velocity with time. Mathematically, it is expressed as:
a = (v – u) /t
Where
a => acceleration
v => final velocity
u => Initial velocity
t => time
With the above information in mind, let us consider the options given in the question above to know which conform to the difinition of acceleration.
For Option 1,
We were told that the tennis ball has the following:
Distance = 4 m
Time = 1.5 s
This talks about the speed and not the acceleration.
Speed = distance / time
For Option 2,
We were only told about the average speed and nothing else.
For Option 3,
We were told that the tennis ball have the following:
Initial velocity (u) = 0 m/s
Final velocity (v) = 14.7 m/s
Time = 1.5 s
This talks about the acceleration.
a = (v – u) /t
For Option 4,
We were only told that the tennis rolls to the right at an average speed. This talks about the average velocity. We need more information like time to justify the acceleration.
From the above illustrations, option 3 gives the correct answer to the question.
