1. [-12 Points] DETAILS OSCOLPHYSZO16 7.1.P.002. MY NOTES ASK YOUR TEACHER A 79.0 kg person climbs stairs, gaining 2.70 meters in height. Find the work done (in J) to accomplish this task. :l J 1. 2. [-12 Points] DETAILS OSCOLPHYSZO16 7.1.P.005. MY NOTES ASK YOUR TEACHER Calculate the work done (in J) by a 90.0 kg man who pushes a crate 3.60 m up along a ramp that makes an angle of 200 with the horizontal. (See the figure below.) He exerts a force of 515 N on the crate parallel to the ramp and moves at a constant speed. Be certain to include the work he does on the crate and on his body to get up the ramp. 3. [-l2 Points] - OSCOLPHYSZO16 7.2.P.012. MY NOTES ASK YOUR TEACHER (a) Calculate the force (in N) needed to bring a 1100 kg car to rest from a speed of 80.0 km/h in a distance of 115 m (a fairly typical distance for a non-panic stop). :1 N (b) Suppose instead the car hits a concrete abutment at full speed and is brought to a stop in 2.00 m. Calculate the force exerted on the car and compare it with the force found in part (a). force in (b) = :] force in (a) 4. [-/2 Points] OSCOLPHYSZO16 7.3.WA.024. ASK YOUR TEACHER While leaning out a window that is 6.2 m above the ground, you drop a 0.60 kg basketball to a friend at ground level. Your friend catches the ball at a height of 2.0 m above the ground. Determine the following. (a) the amount of work clone (in J) by the force of gravity on the ball J H (b) the gravitational potential energy (in J) of the ball-earth system, relative to the ground when it is released J H (c) the gravitational potential energy (in J) of the ball-earth system, relative to the ground when it is caught J H (d) the ratio of the change (PEf PEO) in the gravitational potential energy of the ball-earth system to the work done on the ball by the force of gravity =E EIE 5. [-/2 Points] DETAILS OSCOLPHYS2016 7.4.WA.028. TUTORIAL. MY NOTES ASK YOUR TEACHER As shown in the figure below, a box of mass m = 6.40 kg is sliding across a horizontal frictionless surface with an initial speed v; = 2.80 m/s when it encounters a spring of constant k = 2850 N/m. The box comes momentarily to rest after compressing the spring some amount x . Determine the final compression x (in m) of the spring. m 6. [-/2 Points] DETAILS OSCOLPHYS2016 7.4.WA.032. MY NOTES ASK YOUR TEACHER A light spring obeys Hooke's Law. It takes 30.2 J of work to stretch this spring from an elongation of 4.73 cm to an elongation of 5.73 cm. (a) Is the amount of work required to increase the elongation of the spring from 5.73 cm to 6.73 cm greater than, less than, or equal to 30.2 j? greater than O less than O equal to (b) Verify your answer to part (a) by calculating the required work (in ]). J7. [-/2 Points] OSCOLPHYSZO16 7.5.P.025. ASK YOUR TEACHER (a) How high a hill can a car coast up (engine disengaged) if friction is negligible and its initial speed is 86.0 km/h? Em (b) If, in actuality, a 750 kg car with an initial speed of 86.0 km/h is observed to coast up a hill to a height 14.0 m above its starting point, how much thermal energy was generated by friction? :11 (c) What is the average force of friction if the hill has a slope 2.5'1 above the horizontal? :] N (down the slope) 8. [-/2 Points] DETAILS OSCOLPHYS2016 7.5.WA.035.TUTORIAL. MY NOTES ASK YOUR TEACHER As shown in the figure below, a box of mass m = 24.0 kg is sliding along a horizontal frictionless surface at a speed v; = 7.75 m/s when it encounters a ramp inclined at an angle of 0 = 30.0. rough surface frictionless surface The coefficient of kinetic friction between the ramp and the box is u = 0.0704 and the box slides a distance d up the ramp before coming momentarily to rest. (a) Determine the distance (in m) the box slides up the ramp before coming momentarily to rest. m (b) Determine which of the following statements is most correct about the box traveling up the ramp and coming momentarily to rest. O W Net = AKE O Wg = -APEg O W Net = Wcons + noncons O AE = Wnoncons O AE = AKE + APE O all of these9. [-/2 Points] DETAILS OSCOLPHYSZO16 7.6.WA.046. MY NOTES ASK YOUR TEACHER A 3.2 kg box is sliding along a frictionless horizontal surface with a speed of 1.8 m/s when it encounters a spring. (a) Determine the force constant (in N/m) of the spring, if the box compresses the spring 5.3 cm before coming to rest. Em (b) Determine the initial speed (in m/s) the box would need in order to compress the spring by 1.6 cm. CW 10. [-I2 Points] DETAILS OSCOLPHYSZO16 7.7.P.033. MY NOTES ASK YOUR TEACHER What is the cost of operating a 8.00 W electric clock for a year if the cost of electricity is $0.0875 per kW-h? $:l 1