( 5.1 ( ( ( ( Describe ( ( the effects ) ( of ( common forces ) ) ) ) ( -LRB- ( ( ( pushes and ) pulls ) -RRB- ) ) ) ( on ( ( objects , ) ( such ( as ( those ( caused ( by ( ( ( ( ( gravity , ) magnetism ) , ) and ) ( mechanical forces ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (CD 5.1)) (VP (VBD Describe) (NP (NP (DT the) (NNS effects)) (PP (IN of) (NP (JJ common) (NNS forces)))) (PRN (-LRB- -LRB-) (S (VP (VP (VBZ pushes)) (CC and) (VP (VBZ pulls)))) (-RRB- -RRB-)) (PP (IN on) (NP (NP (NNS objects)) (, ,) (PP (JJ such) (IN as) (NP (NP (DT those)) (VP (VBN caused) (PP (IN by) (NP (NP (NN gravity)) (, ,) (NP (NN magnetism)) (, ,) (CC and) (NP (JJ mechanical) (NNS forces)))))))))) (. .)))
5.1 Describe the effects of common forces (pushes and pulls) on objects, such as those caused by gravity, magnetism, and mechanical forces.
(ROOT (S (NP (NNP Gravity) (CC and) (NNP magnetism)) (VP (VBP are) (NP (DT both) (JJ common) (NNS forces))) (. .)))
Gravity and magnetism are both common forces.