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.
OPTION A if it’s for Plato
Hypothesis: Enriched environments will have a positive effect and better performance of the experimental group of animals exposed to toys in comparison to the control group of animals in running in mazes.
Dependent Variable: Control Group
Independent Variable: Exposed/Experimental Group
Answer:
Earth's average surface gravity is about 9.8 meters per second per second. ... The Moon's surface gravity is weaker because it is far less massive than Earth. A body's surface gravity is proportional to its mass but inversely proportional to the square of its radius.
Explanation: