Will the Lamp Slide or Tip When Pushed?

[offthewall]

Homework Statement

This is my first post on the site, so bear with me if this is a little unclear.
A person wants to push a 7.2kg lamp across the floor. (a) Assuming the person pushes at a height of 60 cm above the ground and the coefficient of friction is 0.20, determine whether the lamp will slide or tip over. (b) Calculate the maximum height above the floor at which the person can push the lamp so that it slides rather than tips.

The lamp also has a circular base of radius= 10 cm

Homework Equations

net torque= 0 (if the lamp doesn't tip)

The Attempt at a Solution

The force of gravity on the lamp will be (7.2kg)(9.8 m/s²)=70.6 N
Therefore the normal force, acting at the front of the base will be 70.6 N

The friction force acting against the motion will be (.20)(70.6)= 14.1 N
Therefore the person must push with a force of 14.1 N to move the lamp at a constant speed.

The torque caused by the person = (14.1 N)(.6m)= 8.46 Nm
The torque caused by the normal force at the front of the base= (70.6 N)(.1m)= 7.06

I think that the net torque would cause the lamp to tip, but I'm not sure.

I would really appreciate any help. Thanks!

 

[tiny-tim]

welcome to pf!

hi offthewall! welcome to pf!

The force of gravity on the lamp will be (7.2kg)(9.8 m/s²)=70.6 N
Therefore the normal force, acting at the front of the base will be 70.6 N

The friction force acting against the motion will be (.20)(70.6)= 14.1 N
Therefore the person must push with a force of 14.1 N to move the lamp at a constant speed.

fine so far

The torque caused by the person = (14.1 N)(.6m)= 8.46 Nm
The torque caused by the normal force at the front of the base= (70.6 N)(.1m)= 7.06

I think that the net torque would cause the lamp to tip, but I'm not sure.

no, that doesn't make sense …

i] those torques are in opposite directions, aren't they?
ii] the lamp will tip about the front edge, so take torques about that point