Answer:
Speed of the ball relative to the boys: 25 km/h
Speed of the ball relative to a stationary observer: 35 km/h
Explanation:
The RV is travelling at a velocity of
Here we have taken the direction of motion of the RV as positive direction.
The boy sitting near the driver throws the ball back with speed of 25 km/h, so the velocity of the ball in the reference frame of the RV is
with negative sign since it is travelling in the opposite direction relative to the RV. Therefore, this is the velocity measured by every observer in the reference frame of the RV: so the speed measured by the boys is
v = 25 km/h
Instead, a stationary observer outside the RV measures a velocity of the ball given by the algebraic sum of the two velocities:
v = +60 km/h + (-25 km/h) = +35 km/h
So, he/she measures a speed of 35 km/h.
Explanation:
It is given that,
Distance between wires, d = 3.5 mm = 0.0035 m
Power of light bulb, P = 100 W
Potential difference, V = 120 V
(a) We need to find the force per unit length each wire of the cord exert on the other. It is given by :
Power, P = V × I
This gives,
(b) Since, the two wires carry equal currents in opposite directions. So, teh force is repulsive.
(c) This force is negligible.
Hence, this is the required solution.
(A) For the system consisting of the two blocks, the change in the kinetic energy of the system is equal to work done by gravity on the system.
(D) For the system consisting of the two blocks, the pulley and the Earth, the change in the total mechanical energy of the system is zero.
<h3 /><h3>The given parameters:</h3>The total initial mechanical energy of the two block system is calculated as follows;
When the block m2 reaches the ground the block m1 attains maximum height and the total mechanical energy at this point is given as;
Thus, we can conclude the following before the block m2 reaches the ground;
Learn more about conservation of mechanical energy here: brainly.com/question/332163
Answer:
a. The sound will travel at the speed to both Jill and Jack
b. Jack
Explanation:
a. Doppler effect describes how the frequency of a sound wave changes with regards to an observer that has relative motion to the sound source;
The Doppler effect is given by the following formula;
For a sound that is moving away, as observed by Jill, we have;
For approaching sound, as observed by Jack, we have;
Where;
f = The sound wave's actual frequency
f' = The frequency of the moving sound to the observer
v = The speed of the sound wave
v₀ = The observer's velocity = 0
= The velocity of the source (the automobile honking) of the sound wave
From the above equation, we have that the speed of sound, 'v', is the same to both the source, and the observer although the frequency, and therefore, the wavelength of the sound alternatively increases or decreases
b. From the Doppler effect equation, the person who will hear the highest frequency is given by the formula for the frequency when the sound is approaching the observer, which has the lower denominator
Therefore, given that the automobile is travelling towards Jack, jack will hear the higher frequency