A cement truck when filled weighs 42 000 N. Calculate its mass

In which situation has the independent variable for the experiment been changed? check all that apply. changed from counting the number of duckweed at day 0 and day 14 to counting them every day changed from testing duckweed growth in beakers to testing duckweed growth in large outdoor tanks changed from testing the effect of ph on duckweed growth to testing the effect of light levels on duckweed growth changed from testing the effect of acid ph on duckweed growth to testing the effect of basic ph on duckweed growth

Atomic nuclei of almost all elements consist of

A1.5m wire carries a 2 a current when a potential difference of 52 v is applied. what is the resistance of the wire?