3. Analyze: Friction causes work to be "wasted" as heat (which is why your hands get warm). A. Does friction waste more work on longer or shorter planes? B. How can you tell? C. Why do you think this is? [Hint: Remember the stick presses up on the item. Do your hands get warmer faster if you press them together harder as you rub?] Conjecture: Does friction cause more energy to be wasted if the object is heavier? Why? Use the Gizmo to test this. Describe your results in your notebook or on a separate sheet.

3. Analyze: Friction causes work to be "wasted" as heat (which is why your hands get warm). A. Does friction waste more work on longer or shorter planes? B. How can you tell? C. Why do you think this is? [Hint: Remember the stick presses up on the item. Do your hands get warmer faster if you press them together harder as you rub?] Conjecture: Does friction cause more energy to be wasted if the object is heavier? Why? Use the Gizmo to test this. Describe your results in your notebook or on a separate sheet.

A train moving in the east direction accelerates from rest to \( 36 \mathrm{~km} / \mathrm{h} \) in 20 s . What is the average acceleration during that time interval?

4. Conjecture: Does thiction cause more energy to be wasted if the object is heavier? Why? Use the Gizmo to test this. Describe your results in your notebook or on a separate sheet.

3.- Calcula en joule la energía cinética traslacional que lleva una bala que tiene una masa de 7 gr si la magnitud de su velocidad es de \( 420 \mathrm{~m} / \mathrm{s} \). R 705.6 J

2. For how long must a force of 10 N act on a body at rest of mass 400 grams for said body to reach a speed of \( 20 \mathrm{~m} / \mathrm{s} \) ?