Answer:
(C) Only if it starts moving
Explanation:
We know that work done is given by

So there are two case in which work done is zero
First case is that when force and displacement are perpendicular to each other
And other case is that when there is no displacement
So for work to be done there must have displacement, if there is no displacement then there is no work done
So option (c) will be the correct option
Answer:
The force of gravity on earth, no matter the object is approximately 9.8 m/ s2 . The reason the crumpled paper hits the ground first is because of air resistance. A crumpled piece of paper has less surface area than an piece of paper that is not crumpled. More surface area means more air resistance.
Answer:
19.4 seconds
Explanation:
We have:
m: mass of the car = 1500 kg
v₀: is the initial speed = 19 m/s
: is the final speed = 0 (it stops)
: is the coefficient of kinetic friction = 0.100
First, we need to find the acceleration by using the second Newton's law:


Solving for a:

Now we can find the time until it stops:

Solving for t:

Therefore, the time until it stops is 19.4 seconds.
I hope it helps you!
To raise 1 kg by 1C, it will take 129 joules.
To raise 0.015 kg by (85-22)C, it will take (129*0.015)*22 = 42.57 joules.