3. what average net force is required to stop a 7 kg shopping cart in 2 s if it's initially
traveling at 3.5 m/s?

The force required to stop the shopping cart is, F = 12.25 N

Explanation:

Given data,

The mass of the shopping cart, m = 7 kg

The initial velocity of the shopping cart, u = 3.5 m/s

The final velocity of the shopping cart, v = 0 m/s

The time period of acceleration, t = 2 s

The change in momentum of the cart,

                                       p = m(u - v)

                                          = 7 (3.5 - 0)

                                          = 24.5 kg m/s

The force is defined as the rate of change of momentum. To stop the shopping cart, the force required is given by the formula

                                            F = p / t

                                                = 24.5 / 2

                                                = 12.25 N

Hence, the force required to stop the shopping cart is, F = 12.25 N

graph slopes whilst gas cools, then it is flat whilst conensation to liquid happens, the coolong liquid then graphs as a slope when it solidifies graph is flat

latent heat

conservation of mass

mass before something happens = mass afterwards