21. A 75 kg shopping cart moves at 2 m/s while a 30 kg child on a bike moves at 2 m/s.
Which is easier to stop?
Why?



Answer :

A 30 kg child on a bike is easier to stop than a 75 kg shopping cart, even though they are moving at the same speed of 2 m/s. This is because the child has less mass, which means it has less inertia compared to the shopping cart.

1. Inertia: Inertia is the resistance of an object to changes in its state of motion. The greater the mass of an object, the greater its inertia. In this case, the shopping cart has a higher mass (75 kg) compared to the child on the bike (30 kg).

2. Stopping Distance: When an object is in motion, stopping it requires applying a force in the opposite direction of its motion. The shopping cart, with its higher mass, will require more force to stop compared to the child on the bike.

3. Force of Impact: If both the shopping cart and the child on the bike were to collide with something, the shopping cart would exert a greater force due to its higher mass. This means it would cause more damage in a collision compared to the child on the bike.

In summary, the child on the bike is easier to stop than the shopping cart because of the child's lower mass, resulting in lower inertia, and requiring less force to stop or change its motion compared to the heavier shopping cart.

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