<u>Answer:</u>
Option: D. Gravity is pulling the crash test dummy in the direction the car is moving.
<u>Explanation:
</u>
When a car accelerates from a standing start, the crash test dummy appears to be pressed backward into the seat cushion because the gravity is pulling the crash test dummy in the direction the car is moving.
Basically when the car is starting, the person inside is in static position and the car is going to move. So it is putting a force on the person to move on the same speed. But as the person is sitting static hence gravity is pulling him behind from moving. Hence, The dummy appears to be pressed backward.
Answer:

Explanation:
The general equation for position of Simple harmonic motion is given as:
........(1)
where,
x = Position of the wave
A = Amplitude of the wave
ω = Angular velocity
t = time
In this case, the amplitude is just half the range,
thus,
(Given range = 3cm)
A = 1.5 cm
Now, The angular velocity is given as:

Where, T = time period of the wave =0.27s (given)

or

so, at time t = 55 s, the equation (1) becomes as:

on solving the above equation we get,

here the negative sign depicts the position in the opposite direction of +x
Answer:
So length of pendulum is 143.129 m
Explanation:
We have given period of simple pendulum is 2 sec
We have to find the length of simple pendulum
Let the length of pendulum is l
Acceleration due to gravity
is
Time period is given by 
So 

Squaring both side

l =143.129 m
So length of pendulum is 143.129 m
If the scale reads 650N, then the mass of whoever it is standing on the scale is
(weight) / (gravity) = (650N) / (9.8 m/s²) = 66.3 kilograms .
It's not MY mass, even if I'm the one standing on the scale.
If I stand on a scale and it reads 650 N, the scale is broken.