Lester+Liang

Week 8

01. A loaded sled weighing 85 N rests on a plane inclined at an angle of 20⁰ with the horizontal. The coefficents of static and kinetic friction between the inclined plane and the sled are 0.25 and 0.15 respectively. object movement= kinetic friction

a). What is the least magnitude of the force F, parallel to the plane, that will prevent the sled from slipping down the plane Find force of sled before it starts to move. Static coefficient. Fstatic,max=Coefficent of static*Fn Fstatic,max= Coefficent of static*(w*cos(20))

b). What is the minimum force required to start the sled moving upward? Its switched to Kinetic force b/c the sleds in movement max speed=Forcekinetic*(cos(0))+Forcenatural*(90)+((mass*gravity)*cos(250)) Fx=Fkinetic+(mass*gravity*cos(250)) Fx=Coefficent of kinetic*85+((mass*gravity*cos(250)) Fx=Fk+mgcos(250) Fx=coefficentof kinetic*85+mgcos(250) Fkinetic*sin(0)+Fnatural*sin(90)+(mass*gravity)*c*sin(250)) m(0)=Fnatural+w*sin(250)=Force(y) Fnet=sqrt((Fx^2)+Fy^2)

c). What value of F (force) is required to move the sled up the plane at constant velocity? since there is a constant velocity then that means a=0 sum of forces=0 Object in equilibrium: no acceleration because constant velocity or object is resting Fnet=Mass*acceleration Fnet=0

Week 7: An object is hung from a spring balance attached to the celing of an elevator cab. The balance reads 65 N, when the cab is standing still. What is the reading when the cab is moving upward,

constant speed of 8 m Cart's stationary so acceleration is 0, Because its at a constant speed then there's no acceleration so C*sin(angle)+mass*gravity*sin(angle)=mass*acceleration so once angle is found, a=0 and C=mass*gravity

with a speed 8 m/s while decelerating at a rate of 2.4 m/s² acceleration=-2.4m/s^2 (deceleration) C*sin(angle)+mass*gravity*sin(angle)=mass*(-acceleration) C-mass*gravity=mass*(-acceleration) C=mass(-acceleration)+mass*gravity C=mass(-acceleration+gravity)