two particles are each given a charge of -5 x 10 C what is the force between the charged particles if the distance between them is 2 meters?

How much energy must a refrigerator absorb from 225 g of water so that the temperature of the water will drop from 35°c to 5°c

Give one example to show that when substances are mixed, it may result in a chemical or a physical change depending on the conditions.

Ahot-air balloon takes off from the ground traveling vertically with a constant upward acceleration of magnitude g/4. after time interval δt, a crew member releases a ballast sandbag from the basket attached to the balloon. how many seconds does it take the sandbag to reach the ground? (express your answer in terms of δt)