child is playing on a hill with a cardboard box. The combined mass of child and box is ? = 120 kg. He climbs into box, which is initially at rest, at the top of the hill. The hill is inclined at an angle of 30 degrees with respect to the horizontal. The coefficients of static and kinetic friction between the box and the hill are ?? = 0.4 and ?? = 0.2. Problem 1: For the following questions (a-d), consider that the child has climbed into the box, but it has not yet started moving. a. What is the magnitude of the weight (also known as the gravitational force) acting on the box + child system? b. What is the magnitude of the normal force acting on the box? c. What is the reaction force associated with the normal force in part (b)?

Problem 1: A 2.80kg block is placed on a rough (us=0.540) incline that makes an angle of 52.0° with respect to the horizontal. A pushing force horizontal to the ground is applied to the top of the block (This would make the force have an angle of 52.0° below the surface of the inclined plane, up the plane) to make the block stationary on the plane. What is the minimum pushing force needed to keep the block stationary on the plane? (10 points)

You have been called to testify as an expert witness in a trial involving a head-on collision. Car A weighs 1515 lb and was traveling eastward. Car B weighs 1125 lb and was traveling westward at 43.0 mph. The cars locked bumpers and slid eastward with their wheels locked for 17.5 ft before stopping. You have measured the coefficient of kinetic friction between the tires and the pavement to be 0.750 . What speed ? (in miles per hour) was car A traveling just before the collision? (This problem uses English units because they would be used in a U.S. legal proceeding.).

A child is playing on a hill with a cardboard box. The combined mass of child and box is ? = 120 kg. He climbs into box, which is initially at rest, at the top of the hill. The hill is inclined at an angle of 30 degrees with respect to the horizontal. The coefficients of static and kinetic friction between the box and the hill are mu s = 0.4 and mu k = 0.2. Consider that the box (with child inside) has begun to slide down the hill (you can assume that it has been given a brief push to get it started moving). What is the magnitude of the acceleration of the box?  b. If the hill is 4 m tall, what is the child’s speed when he reaches the bottom? c. At the bottom of the hill, the ground becomes level (horizontal), but the coefficients of friction do not change. How far does the child slide before he comes to a stop? Thank you in advance, it's a lengthy question and I really need help :)

You have been called to testify as an expert witness in a trial involving a head-on collision. Car A weighs 1515 lb and was traveling eastward. Car B weighs 1125 lb and was traveling westward at 42.0 mph. The cars locked bumpers and slid eastward with their wheels locked for 18.5 ft before stopping. You have measured the coefficient of kinetic friction between the tires and the pavement to be 0.750. What speed u (in miles per hour) was car A traveling just before the collision? (This problem uses English units because they would be used in a U.S. legal proceeding.) V = x10 TOOLS mph

Mary and her sister are playing with a cardboard box on the neighborhood hill. Mary climbs into the box, the total mass of the box with Mary in it is 115 kg. The box starts at rest at the beginning of the incline. The hill is at an incline of 28 degrees with respect to the horizontal.The static and kinectic friction between the box and hill is 0.4 and 0.2 respectively. Assume that Mary is now in the box, but has not started to move. a. What is the magnitude of the friction force acting on the box?b. What is the magnitude of the net force acting on the box and child system?c. Will the box slide down the hill, or stay at rest?

A mysterious force acts on all particles along a particular line and always points towards a particular point P on the line. The magnitude of the force on a particle increases as the cube of the distance from that point, that is, F∝ r3, if the distance from the P to the position of the particle is r. It has been determined that the constant of proportionality is 0.23 N/m3, i.e. the magnitude of the force on a particle can be written as 0.23r3, when the particle is at a distance r from the force center. Find the magnitude of the potential energy, in joules, of a particle subjected to this force when the particle is at a distance 0.21 m from point P assuming the potential energy to be zero when the particle is at P.  PE= ?

A 5.95 kg block is sitting on a level floor.  A person is pulling on a rope attached to the block at a 34.84 degree angle above the horizontal (see figure). The force exerted by the person is 7.33 N.  What is the normal force acting on the block from its contact with the floor?

A 20-kg box of oranges slides from rest down a frictionless incline from a height of 5.0 m. A constant frictional force, introduced at point A, brings the block to rest at point B, 19 m to the right of point A. What is the coefficient of kinetic friction, Hk, of the surface from A to B? 5.0 m A 19 m 0.11 0.52 0.26 0.33 0.47

A constant force Fa pushes a 22.5-kg box across a rough horizontal surface. The magnitude of Fa is 185 N and the force is inclined at an angle of θ = 30.0° below the horizontal. The coefficient of kinetic friction between the box and the surface is μk = 0.500. What is the magnitude of the box's acceleration?