Answer:
D. Newton's Third Law of Motion
Explanation:
Newton's law of gravity is definitely not applicable to your hands. So we can cross this bad boy out
Newton's First Law is F=MA (force equals mass times acceleration). This is basically the root of most physics but it isn't the reason for your hand being red after hitting a wall.
Newton's Second law deals with velocities and forces, so even though you are apply a force your are not changing the velocity of the wall much.
Newton's Third Law basically says that for whatever force you apply to an object, that object will apply an equal and opposite force back to you. This is why your hand gets red. When you slap the wall with all your strength, the wall hits your hand back with the same amount of force. The 2nd law can also be seen when you're trying to push a desk and it won't budge. You are pushing on it, but the desk is pushing back. (there are multiple other factors applicable like friction but we physicists like to ignore them :) )
I hope this helps!
Answer:
u = 13.67 m/s
Explanation:
given,
window height = 2 m
window is 7.5 m off the ground on its path up
total distance from the ground to pass the window = 2 + 7.5 = 9.5 m
time taken to go past the window = 1.30 s
using equation of motion
u = 13.67 m/s
hence, the initial velocity of the ball is equal to 13.67 m/s
We can do this with the conservation of momentum. The fact it is elastic means no KE is lost so we don't have to worry about the loss due to sound energy etc.
Firstly, let's calculate the momentum of both objects using p=mv:
Object 1:
p = 0.75 x 8.5 = 6.375 kgm/s
Object 2 (we will make this one negative as it is travelling in the opposite direction):
p = 0.65 x -(7.2) = -4.68 kgm/s
Based on this we know that the momentum is going to be in the direction of object one, and will be 6.375-4.68=1.695 kgm/s
Substituting this into p=mv again:
1.695 = (0.75+0.65) x v
Note I assume here the objects stick together, it doesn't specify - it should!
1.695 = 1.4v
v=1.695/1.4 = 1.2 m/s to the right (to 2sf)
Answer: polar ice reflecting the Sun's light back toward space
<span>You will exert less force the more the lever is longer. So, you need to place your hands as high as possible with the hammers handle.</span>
