HELPPP Which of the following statements about friction is FALSE .
1 ) Friction involves objects that are in physical contact .
2) Friction is less if surfaces are very smooth .
3 ) Friction is always in the direction of the motion .
4) Friction is caused by the uneven surfaces of touching objects

Two particles of masses m and 2m are placed on a smooth horizontal table. a string, which joins these two masses, hangs over the edge supporting a pulley, which suspends a particle of mass 3m.the pulley has negligible mass. the two parts of the string on the table are parallel and perpendicular to the edge of the table. the hanging parts of the string are vertical. find the acceleration of the particle of mass 3m.

The earth remains in orbit around the sun due to the force of gravity. how does the force of gravity exerted by the sun on the earth compare to the force of gravity exerted by the earth on the sun?

Which of the following is an example of units for speed