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.
Answer:
which corresponds to the second option shown: "voltage times amperage"
Explanation:
The electric power is the work done to move a charge Q across a given difference of potential V per unit of time.
Since such electrical work is the product of the potential difference V times the charge that moves through that potential, and this work is to be calculated by the unit of time, we need to divide the product by time (t) which leads to the following final simple equation:
Notice that we replaced the quotient representing charge per unit of time (Q/t) by the actual current running through the circuit.
This corresponds to the second option shown in the question: "Voltage times amperage".
Answer:
open cluster. globular cluster. eclipsing binary
Answer:
An aircraft flying at sea level with a speed of 220 m/s, has a highest pressure of 29136.8 N/m²
Explanation:
Applying Bernoulli's equation, we determine the highest pressure on the aircraft.
where;
P is the highest pressure on the aircraft
is the density of air = 1.204 kg/m³ at sea level temperature.
V is the velocity of the aircraft = 220 m/s
P = 0.5*1.204*(220)² = 29136.8 N/m²
Therefore, an aircraft flying at sea level with a speed of 220 m/s, has a highest pressure of 29136.8 N/m²
To break this problem down, let's start with what we know. The equation given finds one component of the velocity and multiplies it by the change in time. This will not find the acceleration that the first two answers say it will, meaning that the answer isn't A or B.
That leaves us with the final two answers, C and D. If the projectile was launched horizontally and we were trying to find the horizontal displacement, we wouldn't need to use cosθ to find the horizontal velocity, meaning that our answer is most likely C) <span>the horizontal displacement of a projectile launched at an angle!</span><span />
