A car with mass 2500 kilograms travels along a straight level road at 90 km/h. A headwind begins to blow with a force of 200 N causing the car to slow down. Calculate the car’s deceleration.
The book uses the formula F =ma so
3. Book's solution
My confusion with the calculation comes from not knowing why the speed of the car is not considered. It’s a 2500 kg car driving at 90km/h so must have a force or a momentum that is important. Why is the car's speed not considered?
I need to ask a bit more about the question here please:
The second part of the question says
The car travelling at a steady speed collides with a stationary traffic cone of mass 10 kg. The traffic on accelerates in the direction of the car’s motion at 29 m/s2.
Calculate the force applied to the traffic cone by the car.
Book says: Calculation is F =ma = 10 x 29 = 290N
Book asks: What is the force applied by the cone to the car in the collision (hint in the paper is: Newton’s third law of motion).
Answer in the book is 290N. But shouldn’t the answer be -290N because “to every action is an equal and opposite reaction”.