When you climb, earth exerts gravitational force on pack in downward direction(pointing towards the center of earth).
In order to climb, you need to work against work done by gravity on the pack.
Hence work done by you = work done by gravity on pack
= Force x displacement = 70 x 30 = 2100 J.
Answer:
The answer is C.
Explanation:
If there are brake lights then you should drive slower.
-- The net vertical force on the object is zero.
Otherwise it would be accelerating up or down.
-- The net horizontal force on the object is zero.
Otherwise it would be accelerating horizontally,
that is, its 'velocity' would not be constant. That
would contradict information given in the question.
The total net force on the object is the resultant of the
net vertical component and net horizontal component.
Total net force = √(0² + 0²)
= √(0 + 0)
= √0
= Zero.
The correct answer is the last choice on the list.
Also, you know what ! ? It doesn't even matter whether the surface it's
sliding on is frictionless or not.
If the object's velocity is constant, then the NET force on it must be zero.
If it's sliding on sandpaper, then something must be pushing it with constant
force, to balance the friction force, and make the net force zero. If the total
net force isn't zero, then the object would have to be accelerating ... either
its speed, or its direction, or both, would have to be changing.
