Answer:
- Distance between car and the deer when the car stopped = 20 m
- The time required for you to stop once you press the brakes = less than 5 s in order not to hit the deer.
Explanation:
Using the equations of motion,
In the 0.5 s reaction time, we need to first calculate how far he has travelled in that time.
a = 0 m/s² (Since the car is travelling at constant velocity)
x = ?
Initial velocity = u = 20 m/s
x = ut + at²/2
x = 20×0.5 + 0 = 10 m
From that moment,
a = - 10 m/s²
u = initial velocity at the start of the deceleration = 10 m/s
v = final velocity = 0 m/s
x = ?
v² = u² + 2ax
0² = 10² + 2(-10)(x)
20x = 100
x = 5 m
Total distance travelled from when the deer stepped onto the road = 10 + 5 = 15 m
Distance between car and the deer when the car stopped = 35 - 15 = 20 m
b) To determine the time required to stop once you step on the brakes
u = 10 m/s
t = ?
v = 0 m/s²
x = distance from when the brake was stepped on to the deer = 35 - 10 = 25 m
x = (u + v)t/2
25 = (10 + 0)t/2
10t = 50
t = 5 s
Meaning the time required to stop once you step on the brakes is less than 5s.
Answer:
student A or B
Explanation:
A common demonstration is to put a ringing alarm clock or bell in the bell jar, and when the vacuum is created, you can no longer hear the sound of the clock/bell.
The bell is connected to a lab pack or batteries and rung to show pupils it can be heard under normal circumstances. The bell jar is then connected to a vacuum pump using a vacuum plate (see Fig 2) and the air is removed from inside creating a near vacuum. The bell is then again rung. This time however, it cannot be heard.
Small low voltage buzzers can be used as a bell replacement for the bell and work in exactly the same way though teachers generally prefer bells as students may be able to see the hammer moving, proving that it is actually ringing even though they cannot hear it.
Some vacuum pumps are better than others at keeping a strong vacuum though if you cannot completely lose the sound, you will at least notice the volume decreasing.
Sound is simply a series of longitudinal waves travelling from the source, through the air to our ears. Without air present, these waves cannot form and therefore sound cannot be conveyed.
In a longitudinal wave the particles oscillate back and forth in the direction of the wave movement unlike transverse waves which like waves on the sea, single particles travel up and down and not in the direction of the wave.
Because you will not be able to create a perfect vacuum, you may still be able to hear the bell ring slightly. Vibrations from the ringing bell can also travel up to the bung in the bell jar which in turn may resonate the jar slightly. This means you may hear the bell ring, however strong the vacuum. To compensate for this, try to insulate the bell as much as possible from the bell jar. Hanging the bell using elastic cord means some of the vibrations will be absorbed by the cord and not be transferred to the bell jar.
Answer:
|F| = 393750 N
Explanation:
Given that,
Total mass of the train, m = 750000 kg
Initial speed, u = 84 m/s
Final speed, v = 42 m/s
Time, t = 80 s
We need to find the net force acting on the train. The formula for force is given by :
F = ma
So, the magnitude of net force is 393750 N.
Explanation:
After some time t the current does not passing through the circuit
=>so the back emf is zero
=>here the inductor opposes decay of the circuit
- Ldi/dt = Ri
di/dt = - R/Li
di/i = - R/Ldt
now we applying the integration on both sides
log i=-R/Lt+C
here t=0=>i=io
Log io=C
=>Log i=-R/L*t + Log io
logi-Log io=-R/L*t
Log[i/io]=-R/L*t
i/io=e^-Rt/L
i=ioe^-Rt/L
the option D is correct
Via the half-life equation:
Where the time elapse is 11,460 year and the half-life is 5,730 years.
Therefore after 11,460 years the amount of carbon-14 is one fourth (1/4) of the original amount.
