Answer:
Explanation:
When we accelerate in a car on a straight path we tend to lean backward because our lower body part which is directly in contact with the seat of the car gets accelerated along with it but the upper the upper body experiences this force later on due to its own inertia. This force is accordance with Newton's second law of motion and is proportional to the rate of change of momentum of the upper body part.
Conversely we lean forward while the speed decreases and the same phenomenon happens in the opposite direction.
While changing direction in car the upper body remains in its position due to inertia but the lower body being firmly in contact with the car gets along in the direction of the car, seems that it makes the upper body lean in the opposite direction of the turn.
On abrupt change in the state of motion the force experienced is also intense in accordance with the Newton's second law of motion.
Answer:
Length = 2.32 m
Explanation:
Let the length required be 'L'.
Given:
Resistance of the resistor (R) = 3.7 Ω
Radius of the rod (r) = 1.9 mm = 0.0019 m [1 mm = 0.001 m]
Resistivity of the material of rod (ρ) = 
First, let us find the area of the circular rod.
Area is given as:

Now, the resistance of the material is given by the formula:

Express this in terms of 'L'. This gives,

Now, plug in the given values and solve for length 'L'. This gives,

Therefore, the length of the material required to make a resistor of 3.7 Ω is 2.32 m.
Answer:
I answered Number 4 (Solids and Elasticity)
Explanation:
solids and elasticity
The average power output is the ratio between the work done to compress the spring, W, and the time taken, t:

(1)
The work done is equal to the elastic energy stored by the compressed spring:

where

is the spring constant and

is the compression of the spring. If we substitute the numbers, we find:

And now we can use eq.(1) to calculate the average power output: