d.88 n
Explanation:
The force exerted by gravity on the mass is 88N;
Gravitational force is usually experienced by two bodies with masses.
This force causes all objects on earth to accelerate at 9.8m/s².
Force of gravity = mass x acceleration due to gravity
In this case, the force exerted on the object by gravity will be the weight of the object.
Weight is a force applied gravity on a body:
Weight of the masses = Force of gravity = mass x acceleration
Given mass = 9kg
Force of gravity = 9 x 9.8 = 88.2N approximately 88N
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Answer:
The answer is β=0,85 rads
Explanation:
As the ladder is leaning against the building, we can imagine there´s a triangle where 20ft is the hypotenuse and 15ft is the maximum vertical distance between the ladder and the ground, it means, the leg opposite to β which is the angle we need
Let β(betha) be the angle between the ladder and the ground
We also know that 
In this case we will need to find β, this way:

Then β=48,6°
We also have that 2πrads is equal to 360°, in this way we find how much β is in radians:

then we find β=0,85rads
Answer:
2.0 m/s/s
Explanation:
The acceleration of an object is the rate of change of velocity of the object.
Mathematically, it is given by:

where
u is the initial velocity
v is the final velocity
t is the time taken for the velocity to change from u to v
Acceleration is a vector, so it has both a magnitude and a direction.
For the runner in this problem, we have:
u = 0 is the initial velocity (he starts from rest)
v = 8.0 m/s is the final velocity
t = 4.0 s is the time taken
Substituting, we find

Larger stars have a higher amount of fuel in order to keep the process of nuclear fusion going.