Answer:
2. Move faster
Explanation:
Because you lighten the weight and pushed at the same speed it is easier to push the 400-grams than the 800-grams.
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Answer:
55.8 m/s
Explanation:
= Actual frequency of sound emitted by car
= frequency observed when the car moves = 
= Speed of sound = 343 m/s
= Speed of car
Frequency observed is given as


Answer:
The reason is because both are exposed to a virtually infinite heat sink, due to the virtually infinite mass and of the surrounding environment, compared to the sizes of either the cup or the kettle such that the equilibrium temperature,
reached is the same for both the cup and the kettle as given by the relation;

Due to the large heat sink, T₂ - T₁ ≈ 0 such that the temperature of the kettle and that of the cup will both cool to the temperature of the environment
Explanation:
Protons
electrons are negatively charged
neutrons are neutral
The earth is 4.54 billion years old.