Can someone please help me with my Physics homework?

= +245 N '"W "' " ''\" K9. 9 = 9.8 N/kg ' - . . K a I} The pushing force is In the _ - - . - I'll accelerate. X d'reCt'On, V I8 constant, thus the box does not 1% f \"8r Z Fpersl'on on box 2 :1: FN ' E g = .20)(245 N Qt l ) ' ' 52 z = 49 N Subshtute pk = 0.20, FN = 245 N L l Fpersqn on box : 49 N, t0 the right l l 16 g a EVALUATE THE ANSWER ' h 3 . Are the units correct? Force is measured in newtons. I . Does the Slgl'l make sense? The positive sign agrees with the sketch. o Is the magnitude realistic? The pushing force is % the weight of the box. This corresponds with Mk : 020 = l 5. l i i l i 18. Gwen exerts a 36-N horizontal force as she pulls a 52-N sled across a cement sidewalk at constant speed. What is the coefficient of kinetic friction between the Sidewalk and the metal sled runners? Ignore air resistance. 19. Mr. Ames is dragging a box full of books from his office to his car. The box and books together have a combined weight of 134 N. If the coefficient of static friction between the pavement and the box is 0.55, how hard must Mr. Ames push horizon- tally on the box in order to start it moving? j 20. Thomas sits on a small rug on a polished wooden floor. The coefficient of kinetic friction between the rug and the slippery wooden floor is only 0.12. If Thomas weighs 650 N, what horizontal force is needed to pull the rug and Thomas across the floor at a constant speed? 21. CHALLENGE You need to move a 105-kg sofa to a different location in the room. It takes a 403-N force to start the sofa moving. What is the coefficient of static friction between the sofa and the carpet? ? t l .2 l f 4 g i r l i 4' 3. Chapter Self-Check in 73. Jet A 2.75X 10 0-N jet plane is ready for takeoff. If 80. Weather Balloon ox con- the jet's engines supply a constant forward force of weather balloon oth? 6.35X10' N, how much runway will it need to reach The balloon is r his label its minimum takeoff speed of 285 km/h? of 98 N on the Moon? 74. Drag Racing A 873-kg dragster, starting from rest, a. What is the attains a speed of 26.3 m/s in 0.59 s. instruments b. After the ba a. Find the average acceleration of the dragster. instrument 3x SARDINE b. What is the magnitude of the average net force on the instrut CRUDE PROTEIN SON PES MOISTURE MLAE IN the dragster during this time? Sanctions Mackerel Soy OF c. What net c. What horizontal force does the seat exert on the release? driver if the driver has a mass of 68 kg? d. When do SHA THY ( Free 75. The dragster in the previous problem completed a velocity 402.3-m track in 4.936 s. It crossed the finish line going 126.6 m/s. Does the assumption of constant wo table- acceleration hold true? What information is needed her with to determine whether the acceleration was constant! ey fall. Do both 76. Suppose a 65-kg boy and a 45-kg girl use a massless rope in a tug-of-war on an icy, resistance-free surface as in Figure 25. If the acceleration of the girl toward 1 Ib. What the boy is 3.0 m/s2, find the magnitude of the accel- the eration of the boy toward the girl. ume that Figur 81. Whe a re