A box is resting on a rough floor. You then decide to push it forward a distance of 10 m and measure that the thermal energy of the box increases by 100 J. At that point, you push the box back to its initial position. What is the change in the thermal energy of the box for the return portion? 100 J -100 J 200 J -200 J

A 5.0 kg box moves up a ramp with some initial speed. It reaches a vertical height of 3.0 m before momentarily coming to rest. If 100 J of thermal energy is created in the process. Use g = 10 m/s2. Match the answers with questions.

Positive work W done on a system means a. Energy is transferred out of the system b. Energy can change from one form into another c. Energy is transferred into the system d. Total energy of the system is zero

13. A 3000 kg car travelling at 10 m/s rolls down a steep driveway that has a vertical drop of 5.0 m. a) If we ignore friction, what is the car's speed at the bottom of the incline? b) If we include friction, and find that the heat generated along the driveway is 50 000 J, what is the speed of the car at the bottom of the incline?

6 .A 32.0 kg child slides down a long slide in a playground. She starts from rest at a height h1 of 17.00 m. When she is partway down the slide, at a height h2 of 9.00 m, she is moving at a speed of 9.50 m/s.   Calculate the mechanical energy lost due to friction (as heat, etc.).

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give a specific example of a process that has the energy changes and transfers described. (For example, if the question states “ΔEth >0, W = 0,” you are to describe a process that has an increase in thermal energy and no transfer of energy by work. You could write “Heating a pan of water on the stove.”)                                          ΔEth < 0, Q = 0

Similar to the previous problem, we heat about a cup (230 g) of milk (we'll treat it like water, with a specific heat of 4186 J/kg °C) from refrigerator temperature (5.2 °C) to a comfortable drinking temperature (52.5 °C) in order to make a cup of hot chocolate. First, find the energy required to heat this milk. Next, imagine giving a 1,600 kg truck this same amount of kinetic energy. What speed (in m/s) will the truck be travelling?

A student spends part of his day walking between classes, during which time he expends energy at an average rate of 525 W. The remainder of the day he is sitting in class, studying in library, or resting during break; during these activities, he expends energy at an average rate of 178 W. If he expends a total of 8.3 x10^7 J energy in a 24-hour day, how much of the day did he spend walking?

After finishing 2 fried eggs, a sausage, and a cup of latte as breakfast at 8:30 am, Nancy starts biking at constant speed of 15 km/h. Food Energy content in Cal Fried egg 100 Sausage 286 Latte 260 Big apple 125 Slice of 380 pepperoni pizza 12 oz soda 160 Activity Metabolic power (W) Cycling at 15 km/h 400 Walking at5 km/h 280 a) What time Nancy will use up all the intake energy due to biking? b) If Nancy decide to walk back at 5 km/h for an hour then bike at 15 km/h, how many slice of pizza she needs to eat together with a can of 12 oz soda and a big apple as lunch?