An electric kettle supplies 20,000J of energy to heat 0.5kg of water. What is the
temperature change? The specific heat of the water is 4200J/(kg*C)

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)