Aball is thrown upwards from the ground of a tower with a speed of 20 metre per second . there is a window in the tower at the height of 15 m from the ground . how many times and when will the ball pass the window?

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?