A race car accelerates on a straight road from rest to speed of 180 km/hr in 25s . Assuming uniform acceleration of the car thro
1 answer:
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Answer:
<em>1. False</em>
<em>2. True</em>
<em>3. False</em>
<em>4. True</em>
Explanation:
<u>Conservation of Momentum</u>
According to the law of conservation of linear momentum, the total momentum of the system formed by both pucks won't change regardless of their interaction if no external forces are acting on the system.
The momentum of an object of mass ma moving at speed va is
The total momentum of both pucks at the initial condition is
Both pucks are moving to the right and puck B has twice the mass of puck A (let's call it m), thus
We are given
The total initial momentum is
At the final condition, both pucks stick together, thus the total mass is 3m and the final speed is common, thus
Equating the initial and final momentum
Solving for v'
1. Compute the initial kinetic energy:
The final kinetic energy is
As seen, part of the kinetic energy is lost in the collision, thus the statement is False
2. The initial speed of puck B was 2 m/s and the final speed was 3.33 m/s, thus it increased the speed: True
3. The initial speed of puck A was 6 m/s and the final speed was 3.33 m/s, thus it decreased the speed: False
4. The momentum is conserved since that was the initial assumption to make all the calculations. True
Proven