A pendulum makes 20 oscillations in 4.0s on earth and 40 oscillation on planet X. What is the acceleration due to gravity on planet X?

4g

Explanation:

Given

The time on earth is 4 s for 20 oscillations

i.e. time period for one oscillation is

for planet X it is 40 oscillations in 4 s i.e.

time period is

The time period of a pendulum is given by

where L=length of the pendulum

g=acceleration due to gravity

So, we can write the ratio of the time period of two pendulums as

i.e. 4 times the gravity of the earth

explanation:

newton's third law, for every action there is an equal and opposite reaction.

when jerome paddle in flowing river towards east the net speed of jerome will increase

so the net speed of jerome will be given as

now the speed of paul will be same as it is given as he is running on the ground

so

so here we can say since the speed of jerome is more so he will win the race

now as we know the distance so the time difference is given as

so jerome will reach first and the time difference will be 203.55 s or 3.4 min