A racing car has a mass of 750 kg. It undergoes an acceleration of 4.00 m/s2. What is the net force acting on the car?
1 answer:
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The kinetic energy halfway the hill is
Explanation:
If there are no friction forces acting on the cart, we can apply the law of conservation of energy: the mechanical energy of the cart (which is the sum of potential energy + kinetic energy) must be conserved. So we can write:
where
is the initial potential energy, at point A, with
m = 980 kg (mass of the cart)
(acceleration of gravity)
(height at point A)
is the initial kinetic energy, at point A
, with
(velocity at point A)
is the final potential energy, at point B, where
(height at point B)
is the final kinetic energy, at point B, where
is the velocity at point B
Here we are interested in finding , so by re-arranging the equation and substituting we find:
Learn more about kinetic energy:
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Answer: The frequency heard will be f = 275.675Hz
Explanation: When an object emitting sound is moving, it occurs a phenomenon called Doppler shift or Doppler effect. What happens is that the sound gets higher when the moving object comes closer the observer and becomes lower after it passes, This change is due to the quantity of waves that passes through an area in an unit of time.
The formula to calculate the Doppler effect is as follows
f = () · f₀
f is the observed frequency;
c is the speed of sound;
Vs is velocity of the source;
f₀ is the emitted frequency of source;
Substituting and calculating,
f = · 300
f = 275.675 Hz
Thus, the frequency heard by the police officer is 275.675Hz.
Hello!
a) Assuming this is asking for the minimum speed for the rock to make the full circle, we must find the minimum speed necessary for the rock to continue moving in a circular path when it's at the top of the circle.
At the top of the circle, we have:
- Force of gravity (downward)
*Although the rock is still connected to the string, if the rock is swinging at the minimum speed required, there will be no tension in the string.
Therefore, only the force of gravity produces the net centripetal force:
We can simplify and rearrange the equation to solve for 'v'.
Plugging in values:
b)
Let's do a summation of forces at the bottom of the swing. We have:
- Force due to gravity (downward, -)
- Tension force (upward, +)
The sum of these forces produces a centripetal force, upward (+).
Rearranging for 'T":
Plugging in the appropriate values: