37 InertiaInertia (mass): The tendency of an object to resist any change in its motion.25 kg1kg
38 The more mass an object has, the greater its inertia.
39 stay in motion at a constant velocity unless a net force acts on it. Newton’s First LawThe Law of InertiaAn object in movingtends tostay in motion at a constant velocityandan object at restremain at restunless a net force acts on it.
46 (Assume that there is no friction against the car.) Example #1A car with a mass of 2000kg is parked on the side of the road. How much force is needed to accelerate the car at 3m/s²?(Assume that there is no friction against the car.)
58 Math Practice Page: 367, 1-4 Due: 3/10/09 Homework: 12-3Math Practice Page: 367, 1-4Due: 3/10/09
59 A boy pushes forward a cart of groceries with a total mass of 40. 0 kg A boy pushes forward a cart of groceries with a total mass of 40.0 kg. What is the acceleration of the cart if the net force on the cart is 60.0 N?Given:Find:Equation:Solve:
60 What is the upward acceleration of a helicopter with a mass of 5000 kg if a force of 10,000 N acts on it in an upward direction?Given:Find:Equation:Solve:
61 Given: Find: Equation: Solve: An automobile with a mass of 1200 kg accelerates at a rate of 3.0 m/s2 in the forward direction. What is the net force acting on the automobile? (Hint: Solve the acceleration formula for force.)Given:Find:Equation:Solve:
62 Given: Find: Equation: Solve: A 25-N force accelerates a boy in a wheelchair at 0.5 m/s2 What is the mass of the boy and the wheelchair? (Hint: Solve Newton's second law for mass.)Given:Find:Equation:Solve:
72 momentum = mass X velocity Momentum Equationmomentum = mass X velocityp = m x v
73 Example: A car with a mass of 2000 kg is moving with a velocity of 40 m/s. What is its’ momentum? Given: m = 2000 kgv = 40 m/sFind: p = ?Equation: p = m x vSolve: p = 2000 kg x 40 m/sp = 80,000 kg•m/s
74 Conservation of Momentum The total momentum of a group ofobjects does not change unlessoutside forces act on the objects.The momentum before a collisionis equal to the momentumafter the collision.