Question

the image below shows a car crash test dummy at four stages (a, b, c, d) during a frontal collision. at which stage does the dummy first demonstrate newtons first law of motion during the crash?

Explanation:

Step1: Recall Newton's First Law

Newton's First Law states that an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. In a car crash, the dummy will continue moving forward (in its original motion) until a force (like the seatbelt or impact) acts on it.

Step2: Analyze each stage

• In stage A: The car has started to decelerate (due to the crash), but the dummy has not yet started to show the tendency to move forward relative to the car's new - decelerated state.
• In stage B: The car has further decelerated, and the dummy, which was in motion (with the initial velocity of the car before the crash), starts to move forward relative to the now - slower - moving car. This is the first stage where the dummy's motion (trying to continue its original motion) is evident as per Newton's First Law.
• In stage C and D: The dummy's motion is more pronounced, but it is not the first stage.

Answer:

B