Answer:
Explanation:
Use the one-dimensional equation
where vf is the final velocity of the dog, v0 is the initial velocity of the dog, a is the acceleration of the dog, and t is the time it takesto reach that final velocity. For us:
0 = 2 + -.43t and
-2 = -.43t so
t = 4.7 seconds
<span>553 ohms
The Capacitive reactance of a capacitor is dependent upon the frequency. The lower the frequency, the higher the reactance, the higher the frequency, the lower the reactance. The equation is
Xc = 1/(2*pi*f*C)
where
Xc = Reactance in ohms
pi = 3.1415926535.....
f = frequency in hertz.
C = capacitance in farads.
I'm assuming that the voltage and resistor mentioned in the question are for later parts that are not mentioned in this question. Reason is that they have no effect on the reactance, but would have an effect if a question about current draw is made in a later part. With that said, let's calculate the reactance.
The 120 rad/s frequency is better known as 60 Hz.
Substitute known values into the formula.
Xc = 1/(2*pi* 60 * 0.00000480)
Xc = 1/0.001809557
Xc = 552.6213302
Rounding to 3 significant figures gives 553 ohms.</span>
Answer:
B
Explanation:
<em>A. His speed is 0 m/s
</em>
<em>B. His velocity is 12 m/s
</em>
<em>C. His velocity is 0 m/s
</em>
<em>D. His acceleration is 12 m/s</em>
Total distance traveled by John = 120 + 120 = 240 meters
Total time taken by John to cover the distance = 10 + 10 = 20 s
<em>Average speed of John = total distance traveled/total time taken</em>
= 240/20 = 12 m/s
Hence, the average speed/velocity of John throughout the journey is 12 m/s.
The correct option is B.
There are two main types of friction, static friction and kinetic friction. Static friction operates between
Answer:
3. 0.5 sec.
Explanation:
A bullet fired horizontally follows a projectile motion, which consists of two independent motions:
- A horizontal motion with constant speed
- A vertical motion with constant acceleration, g = 9.8 m/s^2, towards the ground
The time taken for the bullet to reach the ground can be calculated just by considering the vertical motion:
where y is the vertical position at time t, h is the initial height, and 
is the initial vertical velocity of the bullet.
Since the bullet is fired horizontally, 
. So the equation becomes
And the time that the bullet takes to reach the ground can be found by requiring y=0 and solving for t:
As we can see, in this equation there is no dependance on the initial speed of the bullet: therefore, if the bullet is fired still horizontally but with a different speed, it will still take the same time (0.5 s) to reach the ground.
