Why is friction important for gymnast working on parallel bars

This is for my 8th grade science class, i really don’t understand. can someone me? , lol.

Acar travels in reverse. it covers 150 meters in 12 seconds what is the velocity of the car what is the speed of the car

Currents in dc transmission lines can be 100 a or higher. some people are concerned that the electromagnetic fields from such lines near their homes could pose health dangers. for a line that has current 150 a and a height of 8.0 m above the ground, what magnetic field does the line produce at ground level? express your answer in teslas and as a percentage of the earth’s magnetic field, which is 0.50 g. is this value cause for worry?