The rate of cooling a body can be expressed as dT/dt = -k(T - T) where T

The rate of cooling a body can be expressed as
dT/dt = -k(T - Tα)
where T = temperature of the body (°C), Tα = temperature of the surrounding medium (°C), and k = the proportionality constant (min-1). Thus, this equation specifies that the rate of cooling is proportional to the difference in temperature between the body and the surrounding medium. If a metal ball heated to 90°C is dropped into water that is held at a constant value of Tα = 20°C, use a numerical method to compute how long it takes the ball to cool to 40°C if k = 0.25 min-1.