4. a cinder block is sitting on a platform 20 m high. it weighs 79 n. the block has energy. calculate it.
5. there is a bell at the top of a tower that is 45 m high. the bell weighs 190 n. the bell has energy. calculate it.
6. a roller coaster is at the top of a 72 m hill and weighs 966 n. the coaster (at this moment) has energy. calculate it.
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