Answer:
Force, F = 187.42 N
Explanation:
It is given that,
Mass of boy, m = 30 kg
Acceleration due to gravity, 
Radius of curvature of the roller coaster, r = 15 m
Speed of the car, v = 7.3 m/s
The force acting on the boy are force of gravity and the centripetal force. The net force acting on him is as follows :



F = 187.42 N
So, he press against the seat with a force is 187.42 N. Hence, this is the required solution.
Hello!
Recall the equation for gravitational force:

Fg = Force of gravity (N)
G = Gravitational constant
m1, m2 = masses of objects (kg)
r = distance between the objects' center of masses (m)
There is a DIRECT relationship between mass and gravitational force.
We are given:

If we were to double one mass and triple another, according to the equation:

Thus:

i think its b cause if you were talking about ice it freezes the melts the evaporates to gas
Answer:
Option B. They use thermal updrafts to stay aloft
Explanation:
The sunlight warms the surface of the earth during noon and morning time and when this warming of the Earth's surface is not evenly done or uniform then this gives rise to the thermals. These are the rising air columns and rises when the air nearest to the earth heats up.
This is how some birds like vultures make use of the thermal updrafts to maintain flight.
Answer:
8.4 V
Explanation:
induced emf, e1 = 5.8 V
Magnetic field, B1 = 0.38 T
magnetic field, B2 = 0.55 T
induced emf, e2 = ?
As we know that the induced emf is directly proportional to the magnetic field strength.
When the other parameters remains constant then


e2 = 8.4 V
Thus, the induced emf is 8.4 V.