100 m/ 20 s= 5 m/s.
They were running at a speed of 5 m/s~
Answer:
72km/hr
Explanation:
Speed in Km is usually represented in hours. so if the car is in constant velocity, and if the car travels 36km in 30 min then it travels 72km in 1 hour.
so the speed of the car is 72km/hr
Answer:

Explanation:
The acceleration due to gravity on the surface of the Earth is given by:

where
G is the gravitational constant
M is the mass of the Earth
R is the radius of the Earth
Here we want to find the new Earth radius R' for which the gravitational acceleration at the surface, g', would be 3 times the current value of g:

So we would have

Solving the equation for R', we find
