Answer:
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.
So you need to do 2100 joules of work to lift your pack.
Power is the rate of work done.
Therefore power = work done by you/time(in seconds)
= 2100/600 =3.5 watts
Explanation:
3. It is not changing at that time
Explanation:
If the acceleration of a body is zero at some instant in time, it implies that the velocity is not changing at that point in time. Velocity is the rate of change of displacement with time.
✓Acceleration and velocity shares a very close relationship.
✓ For a body to accelerate, the velocity must change. Acceleration is defined as the rate of change of velocity with time.
✓If at any point, a body moves with constant velocity i.e the velocity does not change with time, the acceleration becomes zero.
✓ For acceleration to occur, a body must change velocity.
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Answer: B. CO
Explanation:
Diatomic molecules are those that are formed by two atoms of the same chemical element (homonuclear diatomic molecule) or different chemical element (heteronuclear diatomic molecule).
In this sense, oxygen is a homonuclear diatomic molecule because it is formed by two atoms of the same element (
) and Carbon monoxide (
) is heteronuclear diatomic molecule.
Sodium Chloride
is not a diatomic molecule because is a product of ionization, but it can be diatomic in its gas phase with a polar covalent bond.
Answer:

Explanation:
We know that from Newton's second law of motion, F=ma hence making acceleration the subject then
where a is acceleration, F is force and m is mass
Also making mass the subject of the formula 
For
and
hence 
Answer:
786.6 N
Explanation:
mass of car, m = 912 kg
initial velocity of car, u = 31.5 m/s
final velocity of car, v = 24.6 m/ s
time, t = 8 s
Let a be the acceleration of the car
Use first equation of motion
v = u + a t
24.6 = 31.5 + a x 8
a = - 0.8625 m/s^2
Force, F = mass x acceleration
F = 912 x 0.8625
F = 786.6 N
Thus, the force on the car is 786.6 N.