You must find the component of the force before calculating
One big application is the manufacture and use of mirrors.
Answer:
1. D
2. D
3. A
The reason why your body goes right and the car car goes left is because your body tries to stay where it was, which is on the right. Your upper body doesn't feel a force and because of that continues in the same direction. Your lower half is pulled out from under you by seat friction to the left, leaving you leaning to the right.
Answer:
We will go in the same direction where the car was was moving before applying brakes
Our speed will be same as that of speed of the car before applying brakes i.e. 30 mph
This is due to law of inertia as we are initially moving with speed 30 mph so the due to inertia of motion of our body after applying brakes we move in the same direction.
Explanation:
As we know by Newton's first law that every object moves in its state of motion or state of rest until and unless some external force will act upon it.
Here we know that car is initially moving with speed 30 mph so our body has state of motion so it will have tendency to move in same direction.
Here when brakes are applied in the car then also our body will move with same speed in same direction due to inertia of motion.
So our body will strike with windshield with the speed of 30 mph.
Let
V the speed of the girl per step
v the speed of the escalator per step
L the length between ground and floor in number of steps
V*60+v*60=L => V+v=L/60
V*90-v*90=L => V-v=L/90
By adding the equations V+v=L/60 and V-v=L/90 we get:
2V=L(3+2)/180
V=5L/360
V = L/72
Time to climb (in steps) with v=0 (escalator standing still) is:
V*t=L
t = L/V
t = L/(L/72)
t =72 steps
The girl will count 72 steps.
