Answer:
False
Explanation:
A book resting on a shelf has no potential energy relative to the shelf, since it has height of zero meters relative to the shelf.
Answer:
True
Explanation:
How to find final velocity
Answer:
Explanation:
The equation or formula for velocity is similar to speed. To figure out velocity, you divide the distance by the time it takes to travel that same distance, then you add your direction to it.
Final answer:
To calculate final velocity, identify the knowns (initial velocity, acceleration, time), determine the unknown (final velocity), use the equation v = vo + at, and solve by substituting values into the equation.
Explanation:
To find the final velocity of an object, you must first:
Identify the known values, such as initial velocity (vo), acceleration (a), and time (t).
Determine the unknown, which is the final velocity (v).
Select the appropriate equation to calculate final velocity. The standard equation used is v = vo + at.
Substitute the known values into the equation and solve for the final velocity.
For example, if the initial velocity is 70.0 m/s, the acceleration is -1.50 m/s², and the time is 40.0 s, you would calculate the final velocity as follows:
v = vo + at = 70.0 m/s + (-1.50 m/s²) (40.0 s) = 10.0 m/s
This calculation reveals that the final velocity of the object after 40 seconds is 10.0 m/s.
stephanie, who has a mass of 75 kg is driving and suddenly slams on her brakes to avoid hitting a student crossing blanco road. she is wearing her seatbelt, which brings her body to a stop at 0.5 seconds. an average foce of 3750 N is exerted on her body during the collision. how fast was she going before applying the brakes?
Answer:
25 m/s
Explanation:
Impulse = change in momentum
F Δt = m Δv
(3750 N) (0.5 s) = (75 kg) (v − 0 m/s)
v = 25 m/s
A current 1A in the human body is extremely dangerous.
a) Estimate the potential difference needed to produce this current.
b) Suggest why your are unlikely to be injured by an electric current in your house.
Please answer both questions.
a) Potential difference needed: 10,000 V
b) Because the potential difference in the house is maximum 230 V
Explanation:
a)
The relationship between current, potential difference and resistance in a conductor is given by Ohm's law:
[tex]V=RI[/tex]
where
V is the potential difference
R is the resistance
I is the current
The resistance of the human body is estimated to be as high as [tex]100,000 \Omega[/tex] for a dry body and as low as [tex]1000 \Omega[/tex] for a wet body: in this problem, we use a value in the middle,
[tex]R=10,000 \Omega[/tex]
Therefore, the potential difference needed to produce a current of
[tex]I=1 A[/tex]
is
[tex]V=(10,000)(1)=10,000 V[/tex]
b)
Here we want to estimate if it is likely or not to get injured by an electric current in a house.
The amount of current that can be fatal is [tex]I=1 A[/tex]. From part a), we saw that in order to produce this current through the human body, a potential difference of
[tex]V=10,000 V[/tex]
is needed.
However, the electricity that reaches the houses and then is connected to the household appliances has a potential difference of
V = 230 V
This value is much lower than 10,000 V, therefore the electricity in the house is unlikely to cause injures to human body.
Learn more about potential difference:
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