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Botsings tussen vervoertuie vind daagliks op die paaie in ons land plaas - NSC Physical Sciences - Question 7 - 2016 - Paper 1
Question 7
Botsings tussen vervoertuie vind daagliks op die paaie in ons land plaas. In een van hierdie botsings bots 'n motor, met 'n massa van 1 650 kg, wat links teen 'n sne... show full transcript
Worked Solution & Example Answer:Botsings tussen vervoertuie vind daagliks op die paaie in ons land plaas - NSC Physical Sciences - Question 7 - 2016 - Paper 1
Step 1
7.1 Bereken die snelheid van die voertuig onmiddellik na die botsing.
Answer
To find the combined velocity after the collision, we will use the principle of conservation of momentum, which states that the total momentum before the collision equals the total momentum after the collision.
The initial momentum of the system can be calculated as:
Where:
- = mass of the minibus = 3050 kg
- = velocity of the minibus = 15 m/s (to the right)
- = mass of the car = 1650 kg
- = velocity of the car = 25 m/s (to the left, thus negative in calculations)
Calculating the momenta:
= 45750 - 41250 = 4500 ext{ kg m/s}$$ Assuming perfect inelastic collision, both vehicles move together after the impact. The combined mass is: $$m_{combined} = m_{b} + m_{m} = 3050 + 1650 = 4700 ext{ kg}$$ Using the conservation of momentum to find the final velocity ($v_{f}$): $$4500 = (4700) v_{f}$$ Thus, $$v_{f} = rac{4500}{4700} ext{ m/s} \ v_{f} ext{ (after collision)} ext{ is approximately } 0.96 ext{ m/s (to the right)}$$.Step 2
7.2 Bewys deur middel van berekening dat die botsings onelasties is.
Answer
To prove that the collision is inelastic, we will show that the total kinetic energy after the collision is less than the total kinetic energy before the collision.
The initial kinetic energy of each vehicle can be calculated using: KE = rac{1}{2}mv^2
Calculating the initial kinetic energies:
- For the minibus: KE_{b} = rac{1}{2} (3050 ext{ kg}) (15 ext{ m/s})^2 = 0.5 imes 3050 imes 225 = 343125 ext{ J}
- For the car: KE_{m} = rac{1}{2} (1650 ext{ kg}) (25 ext{ m/s})^2 = 0.5 imes 1650 imes 625 = 515625 ext{ J}
Total initial kinetic energy:
Now, the final kinetic energy after the collision:
= 0.5 imes 4700 imes 0.9216 = 21635.76 ext{ J}$$ Since the total kinetic energy after the collision (21635.76 J) is significantly less than the total kinetic energy before the collision (858750 J), we can conclude that the collision is inelastic.Step 3
7.3 Verduidelik hoe frmmelsones kan help om noodlottige en ernstige beserings te verminder.
Answer
Crumple zones in a car are designed to absorb the energy of impact during a collision, which increases the duration of the collision. This longer impact time reduces the force experienced by the passengers, as the force can be described by the impulse-momentum theorem.
The equation governing this phenomenon is: F_{net} = rac{ riangle p}{ riangle t}
Where:
- is the net force,
- is the change in momentum, and
- is the time over which the change occurs.
As the time () increases during a collision, the net force () decreases. By providing crumple zones that deform on impact, the car allows for a more gradual deceleration, which minimizes the risk and severity of injuries to passengers.
Thus, the magnitude of the force felt by passengers is reduced, thereby decreasing the likelihood of serious injuries.