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Chapter 4 Review Question • What is the SI unit of force? Answer • Newton Question • A 1850 kg car is moving to the right at a constant speed of 1.44 m/s. What is the net force on the car? Answer • Zero Question • What acceleration would you give a 24.3 kg box if you push it horizontally with a net force of 85.5 N? Answer • 3.52 m/s2 Question • What net force is required to give a 25 kg suitcase an acceleration of 2.2 m/s2 to the right? Answer • 55 N to the right Question • Find the normal force acting on 5.5 kg laundry basket that is at rest on a ramp inclined at 12⁰ above the horizontal. Answer • 54 N Question • Which is usually greater, the maximum force of static friction or the force of kinetic friction? Answer • Maximum force due to static friction Question • A 95 kg clock initially at rest on a horizontal floor requires a 650 N horizontal force to set it in motion. After the clock is in motion, a horizontal force of 560 N keeps it moving with a constant velocity. Find µs and µk between the clock and the floor. (1 point each) Answer • µs = 0.70 • µk = 0.60 Question • A box slides down a 30.0⁰ ramp with an acceleration of 1.20 m/s2. Determine the coefficient of kinetic friction between the box and the ramp. Be careful with direction! Answer • 0.436 Question • A clerk moves a box of cans down an aisle by pulling on a strap attached to the box. The clerk pulls with a force of 185.0 N at an angle of 25.0⁰ with the horizontal. The box has a mass of 35.0 kg, and the coefficient of kinetic friction between the box and the floor is 0.450. Find the acceleration of the box. Answer • 1.4 m/s2 down the aisle Question • What are 2 possible states of motion an object might be experiencing if it is in equilibrium? Be specific! (1 point each) Answer • At rest • constant speed in a straight line Question • A smart car and a hummer collide. Which car experiences the greater force? Answer • Force is equal on both cars Question • A girl on a sled coasts down a hill. Her speed is 7.0 m/s when she reaches level ground at the bottom. The coefficient of kinetic friction between the sled’s runners and the hard, icy snow is 0.050, and the girl and the sled together weigh 645 N. How far does the sled travel on level ground before coming to a rest? Answer • 49 m Question • In what direction does the normal force ALWAYS act? Answer • Perpendicular to the contact surface Question Question • Find the weight of the picture. Answer • 42.4 N Question • Justin Bieber runs into CeeLo Green and they collide. Who has the greater acceleration and why? Answer • Justin Bieber because he has a smaller mass Question • The sign has a mass of 10 kg. Find the tension in each cable. Answer • 56.6 N Question • A bag of sugar has a mass of 2.26 kg. What is its weight in newtons on the moon, where the acceleration due to gravity is one-sixth that of Earth? Answer • 3.7 N Question • Name one example of a field force Answer • Gravitational force, magnetism Question • A freight train has a mass of 1.5 x 107 kg. If the locomotive can exert a constant pull of 7.5 x 105 N, how long would it take to increase the speed of the train from rest to 85 km/h? Answer • 470 s Question • What is the tendency of objects to NOT accelerate called? Answer • inertia Question • What is the vector sum of all external forces acting on an object called? Answer • Net force Question • What is the SI unit of mass? Answer • kilogram Question • What is the mass of a 63 kg object on Venus where the acceleration due to gravity is 5.8 m/s²? Answer • 63 kg silly!