When she reaches the top, she has more potential energy than she had at the bottom.
Potential energy = (mass) x (gravity) x (height)
= (40 kg) x (9.8 m/s²) x (5 m)
= 1,960 more joules .
Power = (energy) / (time)
= (1,960 joules) / (7 seconds)
= 280 watts
(about 0.375 horsepower)
Answer:
4) True. The change of direction needs an unbalanced force
Explanation:
Let us propose the resolution of the problem using Newton's second law.
F = m a
As the car is spinning the acceleration is centripetal
a = v2.r
F = m v2 / r
We can see that as the velocity of a vector even if its module does not change, the change of direction requires an external force.
Now we can analyze the statement if they are true or false
1) and 3) False, even when the speed changes, the direction changes
2) False with the speed change can be determined
4) True. The change of direction needs an unbalanced force
5) False are different things. the direction is where it is going and the speed is the magnitude of the vector
What happens is that if u put gas in a ball and placed in a hot climate it will start burning Bc u have gas inside the ball
