Dynamics: Forces and Newton's Law of motion

Newton's Second law of motion: Concept of a system :- What Acceleration Can a Person Produce when Pushing a Lawn Mower?Suppose that the net external force (push minus friction) exerted on a lawn mower is 51 N (about 11 lb) parallel to the ground. The mass of the mower is 24 kg. What is its acceleration? o What Rocket Thrust Accelerates This Sled? The acceleration of a baseball is proportional to the net force acting on it. The sled's initial acceleration is 49misz,the mass of the system is 2100 kg, and the force of friction opposing the motion . Newton's first law of motion: Inertia Which has more mass: a kilogram of cotton balls or a kilogram of gold? . A demonstration of inertia. (a) (b) (c)o The forces on an airplane in flight heading eastward are as follows: gravity = 16.0 kN, downward; lift = 16.0 W, upward; thrust = 1.8 kN, east; and drag = 0.8 kN, west. (Lift, thrust, and drag are three forces that the air exerts on the plane.) What is the net force on the plane? 1. A mixed martial artist kicks his opponent in the nose with a force of 200 newtons. Identify the action-reaction force pairs in this interchange. (A) foot applies 200 newton force to nose; nose applies a smaller force to foot because foot has a larger mass. (B) foot applies 200 newton force to nose; nose applies a smaller force to foot because it compresses. (C) foot applies 200 newton force to nose; nose applies a larger force to foot due to conservation of momentum. D) foot applies 200 newton force to nose; nose applies an equal force to the foot.2. Joanne exerts a force on a basketball as she throws the basketball to the east. Which of the following is always true? (A) Joanne accelerates to the west. (B) Joanne feels no net force because she and the basketball are initially the same object. (C) The basketball pushes Joanne to the west. (D) The magnitude of the force on the basketball is greater than the magnitude of the force on Joanne.3. A book and a feather are pushed off the edge of a cliff simultaneously. The book reaches the bot- tom of the cliff before the feather. Correct statements about the book include which of the following? Select two answers. (A) The book has a greater mass than the feather and experiences less air resistance. The book has a greater mass than the feather and experiences a greater net force. (C) The book has a greater cross-sectional area than the feather and experiences less air resistance. The book has a greater cross-sectional area than the feather and experiences more air resistance.4. A force Fis applied perpendicular to the top of a box of mass m sitting on an incline of angle 0. What is the mag- nitude of F such that the normal force of the incline on the box is equal to the weight of the box? (A) mgcose (B) mg(1-cose) (C) mg(1-sine) (D) mg(1+sine)