A dog is 10 m from a cat, whose speeds are 6 and 5 m / s, respectively. What time does the dog require to catch the cat?
1 answer:
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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:
Explanation:
Potential energy =
Answer:
F' = 64 F
Explanation:
The electric force between charges is given by :
Where
q₁ and q₂ are charges
r is the distance between charges
When each charge is doubled and the distance between them is 1/4 its original magnitude such that,
q₁' = 2q₁, q₂' = 2q₂ and r' = (r/4)
New force,
Apply new values,
So, the new force becomes 64 times the initial force.