Answer:
Gravity as well as electrostatic and magnetic attraction and repulsion provide real life examples of forces being exerted by one object on another without them being in contact with each other.
Explanation:
Hope that helps!:)
It's gotta be purple!!!!!!!!!!!!!!!
Answer:
Wind the long piece of thin wire around the uniform glass rod multiple times, find the length of the total diameters using the metre ruler, and divide by the number of times you wound it around the rod.
Explanation:
Since the diameter of one long piece of thin wire is too thin to be measured by a metre ruler, you can wind it multiple times and push it side by side to get a length you can measure.
For example, if you wound it around 20 times and the total length of 20 diameters of the wire side-by-side is 2.0 cm, one winding, which is the diameter would be 2.0cm ÷ 20 = 0.10cm or 1mm.
Answer: -49m/s.
Explanation:
As the rock only falls, we will assume that the initial vertical velocity is zero.
We neglect the air friction, so the only force acting on the rock is the gravitational force, this means that the acceleration is -g = -9.8m/s^2.
Then we can write:
a(t) = -9.8m/s^2
To write the velocity of the rock, we must ingrate over time and get:
v(t) = (-9.8m/s^2)*t + v0
where v0 is the initial vertical velocity, and as we said above, v0 = 0m/s
Then the vertical velocity as a function of time is:
v(t) = (-9.8m/s^2)*t
Now, the question is:
"...If a rock falls for 5 seconds near the surface of the earth and with no air friction, it will reach a velocity of..."
Then we need to evaluate the velocity equation in t = 5 seconds.
v(5s) = (-9.8m/s^2)*5s = -49m/s.
Answer:
Work done, W = 0 J
Explanation:
It is given that,
Mass of the bag, m = 7 kg
If a person carries a bag of groceries 1.2 m above the ground at constant speed across a 2.7 m room. We need to find the amount of work done on the bag he the process. It is given by :
Where
θ = angle between the force and the direction of motion. Here, θ = 90° (its weight is acting vertically downward and it is moving forward)
Since, cos(90) = 0
⇒ Work done, W = 0 J
So, the work done on the bag is zero. Hence, the correct option is (b) "0 J".
