Two trolleys A and B of mass 3.2 kg and 2.6 kg respectively are held at rest on a straight horizontal, frictionless track, with a compressed spring between them, as shown in the diagram below - NSC Physical Sciences - Question 4 - 2024 - Paper 1
Question 4
Two trolleys A and B of mass 3.2 kg and 2.6 kg respectively are held at rest on a straight horizontal, frictionless track, with a compressed spring between them, as ... show full transcript
Worked Solution & Example Answer:Two trolleys A and B of mass 3.2 kg and 2.6 kg respectively are held at rest on a straight horizontal, frictionless track, with a compressed spring between them, as shown in the diagram below - NSC Physical Sciences - Question 4 - 2024 - Paper 1
Step 1
State the principle of conservation of linear momentum in words.
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Answer
In an isolated system, the total (linear) momentum remains constant. This means that the total momentum before the event is equal to the total momentum after the event.
Step 2
Calculate the distance travelled by trolley B in 1.3 s.
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Answer
To calculate the distance travelled by trolley B, we can use the formula:
extDistance=extVelocityimesextTime
Given that trolley A moves with a constant velocity of 0.4 m s^-1 to the left, we need to determine the velocity of trolley B. According to the information provided, the time taken for trolley B to reach the end of the track is 1.3 s, and we can express the distance for trolley B as:
extDistanceB=vBimest=vBimes1.3
From the conservation of momentum, we have:
3.2imes(−0.4)+2.6imesvB=0
Solving this gives:
v_B = rac{3.2 imes 0.4}{2.6} = 0.4923 ext{ m s}^{-1}
Thus, the distance:
extDistanceB=0.4923imes1.3=0.64extm
Step 3
Calculate the time it took the spring to extend to its natural length.
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Answer
The average force exerted by the spring on each trolley is given as 4.2 N. Using Newton's second law of motion, we can express the relationship as:
v = u + at \
v = 0 ext{ (initial velocity)} + (1.3125 imes t)\
ext{Using the final velocity from previous calculations,}\
0.49 = 0 + (1.3125 imes t)\
t = rac{0.49}{1.3125} = 0.37 ext{ s}
Step 4
How does the magnitude of the velocity of trolley B after the spring has fallen to the track? Write only GREATER THAN, LESS THAN or EQUAL TO. Explain the answer.
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Answer
The magnitude of the velocity of trolley B after the spring has fallen to the track will be LESS THAN the velocity of trolley A after the spring has extended because trolley C, which has a larger mass, is now present in the system. The larger mass will result in a smaller acceleration for trolley C after the same force acts upon it, thus reducing the final velocity of trolley B after the spring is released.