Explanation:
Given that,
Mass of the car, m₁ = 1250 kg
Initial speed of the car, u₁ = 7.39 m/s
Mass of the truck, m₂ = 5380 kg
It is stationary, u₂ = 0
Final speed of the truck, v₂ = 2.3 m/s
Let v₁ is the final velocity of the car. Using the conservation of momentum as :



So, the final velocity of the car is 2.5 m/s but in opposite direction. Hence, this is the required solution.
Answer:
Speed of the speeder will be 28 m/sec
Explanation:
In first case police car is traveling with a speed of 90 km/hr
We can change 90 km/hr in m/sec
So 
Car is traveling for 1 sec with a constant speed so distance traveled in 1 sec = 25×1 = 25 m
After that car is accelerating with
for 7 sec
So distance traveled by car in these 7 sec

So total distance traveled by police car = 224 m
This distance is also same for speeder
Now let speeder is moving with constant velocity v
so 
v = 28 m/sec
Answer:
MATERIAL MEDIUM
Explanation:
Wave is a disturbance that travels through a medium and transfer energy from one point to another without causing any permanent displacement of the medium itself. The two forms of wave are the mechanical wave and the electromagnetic waves.
Mechanical wave is a wave with requires MATERIAL MEDIUM for its propagation. This means that before wave can be propagated at times, material medium is needed e.g a ripple tank. A ripple tank is a mechanical device that generates waves using an instrument called stroboscope attached to it. This kind of wave requires an external source before it can propagate compared to electromagnetic waves that does not require material medium for its propagation.
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