Riding a bicycle on a flat, smooth surface is a lot
easier than riding it along a bumpy surface or up a
hill. A bumpy surface creates more friction with
your bike tires than a smooth surface does, and
going up a hill means fighting gravity. Write about
a time you had to ride a bicycle on a difficult
surface. What did you have to do to adjust your
riding?

When a book falls from a shelf to the ground without anyone pushing on it, no work is done on the book. true or false

Asmall object with mass 0.200 kg swings back and forth on the lower end of a light rope that is 3.00 m long. the upper end of the rope is attached to the ceiling. as the object swings through its lowest position, where the rope is vertical, the speed of the object is 5.80 m/s. at this point in the motion, what is the tension in the rope? (use g = 9.80 m/s2.)

Consider a 1000 w iron whose base plate is made of 0.5 cm thick aluminum alloy 2024-t6 (ρ = 2770 kg/m3 and cp = 875 j/kg°c). the base plate has a surface area of 0.03 m2. initially, the iron is in thermal equilibrium with the ambient air at 22°c. assuming 90% of the heat generated in the resistance wires is transferred to the plate, determine the minimum time needed for the plate temperature to reach 200°c.