1. Describe the motion of the race car. The race car has forces acting: Up 2000 N, Down 2000 N, Left 6000 N, Right 8000 N. Calculate the net horizontal force: $$F_{net_x} = 8000 - 6000 = 2000\,N$$. Calculate the net vertical force: $$F_{net_y} = 2000 - 2000 = 0\,N$$. Since net force to the right is positive and nonzero, the race car is speeding up in the forward direction. 2. Find net force on each box. Box A: Left 60 N, Right 20 N. $$F_{net} = 20 - 60 = -40\,N$$ (left direction). Box B: Up 50 N, Down 25 N. $$F_{net} = 50 - 25 = 25\,N$$ (upward). 3. Find reading on fourth scale (bear weight problem). Total weight = 1500 N. Sum of known scales: 400 + 300 + 250 = 950 N. Reading on fourth scale: $$1500 - 950 = 550\,N$$. 4. Compare inertia of bowling ball to tennis ball. Mass bowling ball = 6 kg, tennis ball = 0.06 kg. Inertia proportional to mass. Ratio: $$\frac{6}{0.06} = 100$$. Bowling ball has 100 times more inertia than tennis ball. 5. Free-body diagram forces. a. Net force = 100 N to the right: push force right > friction. b. Equilibrium: push force equals friction; net force zero. 6. Acceleration of 100 kg bag of sand with weight 100 N. Weight relates to gravitational force: $$W = mg$$. Given $$W = 100\,N$$ and mass $$m = 100\,kg$$. Calculate acceleration due to gravity: $$g = \frac{W}{m} = \frac{100}{100} = 1\,m/s^2$$. When dropped, acceleration is $$1\,m/s^2$$ (assuming no air resistance).