Question
A shopper pushes a grocery cart 20m at constant speed on level ground against a 35N frictional force. He pushes in a direction 25 degrees below the horizontal. What is the work done on the cart by gravity?
I know you can use W=Fdcos(theta) where F=mass*gravity. BUT, no mass is given so there must be some other way.
Help!
I know you can use W=Fdcos(theta) where F=mass*gravity. BUT, no mass is given so there must be some other way.
Help!
Answers
gravity is doing no work because its perpendicular to the motion
mass is not required. Constant speed means zero acceleration.
Fcos(theta) - Ff=m*a
Fcos(theta) - Ff=0
F cos(25) =35
0.9063F=35
F=38.62N
W=Fcos(theta)*d
W= 38.62 cos(25)*20
W=700J
Fcos(theta) - Ff=m*a
Fcos(theta) - Ff=0
F cos(25) =35
0.9063F=35
F=38.62N
W=Fcos(theta)*d
W= 38.62 cos(25)*20
W=700J