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.
A 100 g cart is moving at 0.5 m/s that collides elastically from a stationary 180 g cart. Final velocity is calculated to be 0.25m/s.
Collision in which there is no net loss in kinetic energy in the system as a result of the collision is known as elastic collision . Momentum and kinetic energy both are conserved quantities in elastic collisions.
Collision in which part of the kinetic energy is changed to some other form of energy is inelastic collision.
For an elastic collision, we use the formula,
m₁V₁i+ m₂V₂i = m₁V1f + m₂V₂f
For a perfectly elastic collision, the final velocity of the 100g cart will each be 1/2 the velocity of the initial velocity of the moving cart.
Final velocity = 0.5/2
=0.25 m/s.
To know more about elastic collision, refer
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Answer:
Option C
Explanation:
Hydrocarbon + Oxygen = Carbon dioxide + Water
is example of combustion reaction
Answer:
True
Explanation:
This can be explained by the special theory of relativity for length contraction.
Length contraction is observed in the direction of motion of an object when an object moves with speed closer to the speed of light.
The length of the rocket in this case, appears shorter to the observer on earth in the stationary reference frame which is improper frame whereas the traveler in the rocket is in the same inertial frame which is proper for the rocket's size measurement.