<span>After an exoplanet has been identified using a given detection method, scientists attempt to identify the basic properties of the planet which can tell us what it might be made of, how hot it might be, whether or not it contains an atmosphere, how that atmosphere might behave, and finally, whether the planet may be suitable for life. It is often useful to first determine basic properties of the parent star (such as mass and distance from the Earth). This is then followed by the use of planetary detection methods to calculate planetary mass, radius, orbital radius, orbital period, and density. The density calculation will provide clues as to what the planet is made of and whether or not it contains a significant atmosphere.
Mass and Distance of Parent Star
The mass and distance of an exoplanet's parent star must often be calculated first, before certain measurements of the exoplanet can be made. For example, determining the star's distance is an important step in determining a star's mass (see below). Knowing the mass of a star then allows the mass of the planet to be measured, for example when using the Radial Velocity Method.</span>
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What is the magnitude of the electric field at the dot in the figure? (E=? V/m) What is the direction of the electric field at the dot in the figure? 1. to the left 2. to the right 3. upward 4. downward Thanks!
Answer:
The coefficient of friction is 0.38.
Explanation:
The free body diagram is drawn below.
Let 
be frictional force acting in the backward direction as shown. Let the coefficient of friction be 
. Let 
be the normal reaction force acting on the bag.
Given:
Mass of the bag is, 
Force acting at 
° is 
Acceleration due to gravity is, 
The force F can be resolved into its components as 
and 
Therefore,
Now, as there is no acceleration in vertical direction, therefore,
Sum of upward forces = Sum of downward forces
Now, as the bag is moving at a constant speed, so acceleration in the horizontal direction is also zero as acceleration is the rate of change of velocity.
Therefore, backward force = forward force.
Now, frictional force is given as:
Therefore, the coefficient of friction is 0.38.
