A light spring with a force constant of 22 N/m is connected to a wall and to a 1.8-kg toy bulldozer. When the electric motor in the bulldozer is turned on, it stretches the spring for a distance of 40 cm before its tread begins to slip on the floor and it accelerates back towards the wall at a rate of 0.784 m/s2. What is the coefficient of dynamic friction between the treads and the floor?

An electron and a proton have the same kinetic energy upon entering a region of constant magnetic field and their velocity vectors are perpendicular to the magnetic field. suppose the magnetic field is strong enough to allow the particles to circle in the field. note: you'll need to look up the masses for an electron and proton. 1) what is the ratio of the radii of their circular paths rp/re?

Acar moves at 12m/s and coasts up a hill with a uniform acceleration of -1.6m/s2. how far has it traveled after 6.0s?

On a mild saturday morning while people are working inside, the furnace keeps the temperature inside the building at 23degreesc. at noon the furnace is turned off, and the people go home. the temperature outside is a constant 16degreesc for the rest of the afternoon. if the time constant for the building is 3 hr, when will the temperature inside the building reach 18degreesc? if some windows are left open and the time constant drops to 2 hr, when will the temperature inside reach 18degreesc?