)
5
-5
1 2 3
4
5
Other than at t = 0, when is the velocity of
the object equal to zero?
1. 5.0 s
2. 4.0 s
3. 3.5 s
4. At no other time on this graph. correct
5. During the interval from 1.0 s to 3.0 s.
Explanation:
Since vt =
Z t
0
a dt, vt
is the area between
the acceleration curve and the t axis during
the time period from 0 to t. If the area is above
the horizontal axis, it is positive; otherwise, it
is negative. In order for the velocity to be zero
at any given time t, there would have to be
equal amounts of positive and negative area
between 0 and t. According to the graph, this
condition is never satisfied.
005 (part 1 of 1) 0 points
Identify all of those graphs that represent motion
at constant speed (note the axes carefully).
a) t
x
b) t
v
c) t
a
d) t
v
e) t
a
Answer:
The engine would be warm to touch, and the exhaust gases would be at ambient temperature. The engine would not vibrate nor make any noise. None of the fuel entering the engine would go unused.
Explanation:
In this ideal engine, none of these events would happen due to the nature of the efficiency.
We can define efficiency as the ratio between the used energy and the potential generable energy in the fuel.
n=W, total/(E, available).
However, in real engines the energy generated in the combustion of the fuel transforms into heat (which heates the exhost gases, and the engine therefore transfering some of this heat to the environment). Also, there are some mechanical energy loss due to vibrations and sound, which are also energy that comes from the fuel combustion.
A) 1 rev = 2π rad. Using this ratio, you can find the rad/s: 1160 rev/min x 2π rad/rev x 1 min/60 s = 121.5 rad/s
b) You can find linear speed from angular speed using this equation (note the radius is half the diameter given in the question): v = ωr = 121.5 rad/s x 1.175 m = 142.8 m/s
c) You can find centripetal acceleration using this equation: a = v^2/r = (142.8 m/s)^2 / 1.175 m = 17 355 m/s^2
Answer:
1) D, 2) D, 3) B, 4) B, 5) C
Explanation:
You are asked to select the correct answer
1) The conservation of energy is one of the most important principles of physics that allows solving countless problems in life.
the correct answer is D
2) when a body falls, the gravitational potential energy is transformed into kinetic energy and both are transformed into thermal energy
the correct answer is D
3) When the gravitational potential energy is maximum, the kinetic energy is minimum and when the kinetic energy is maximum, the gravitational energy is minimum.
Correct answer B
4) speed is defined by
v = x / t
so the correct answer is B in the SI system
5) when we repeat a measurement several times, the random or statistical errors decrease, therefore the confidence of the measurement increases.
The correct answer is C
Answer:
The person feels cool at first because the swimming pool water is usually cool and he/she has that water on his body. But when it evaporates, the cool air directly touches his body and that's why he/she feels cold.
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