Acceleration can be all the following except: changing direction
changing distance
speed up
slowing down

Abearing is designed to a reduce friction b. support a load c. guide moving parts such as wheels, shafts and pivots d. all of the above

Which of the following is the main energy source for the sun? a. fission of hydrogen b. fusion of hydrogen c. fusion of helium d. fission of iron

Suppose that 27 j of work is needed to stretch a spring from its natural length of 6 m to a length of 9 m. (a) how much work is needed to stretch the spring from 12 m to 14 m? j (b) how far beyond its natural length will a force of 78 n keep the spring stretched?