S.I. Unit of mass is Kilogram which is denoted by Kg
In short, Your Answer would be Option C
Hope this helps!
F=mg=Gm1m2/r^2
g=Gm2/r^2
g=2Gm2/(2r)^2=2Gm2/4r^2=Gm2/2r^2
So since there is half times the gravity on this unknown planet that has twice earth's mass and twice it's radius, then the person can jump twice as high. 1.5*2= 3m high
Answer:
At an angle of 
Explanation:
Assume the river flows from East to West so for the swimmer to cross across it, assume he crosses it from West to East.
The resultant speed will be given by

ANSWER
Velocity of the mass reaches zero
EXPLANATION
We want to identify what hapens to a mass attached toa a spring at maximum displacement.
When a mass attached to a spring is at its maximum position of displacement, the direction of the mass begins to change. This implies that the velocity of the mass will reach zero.
Hence, at maximum displacement, the velocity of the mass reaches zero.
Some examples of stable system are:
1) functions of sine
2) DC
3) signum
4) unit step
5) cosine.
Happy Studying! ^^