Answer:
3.07 m/s
Explanation:
We know that from kinematics equation
and here, a=g where v is the final velocity, u is the initial velocity, a is acceleration, s is the distance moved, g is acceleration due to gravity
Making u the subject then
Substituting v for 6.79 m/s, s for 1.87 m and g as 9.81 m/s2 then
Example of weathering and erosion:
- The ocean beating up against the cliff of a wall and slowly wearing away rock
- A river flowing through river banks and the bank slowly stretching apart further and further as time goes on
- Water freezes in a crack on a rock. As the water freezes, the crack expands on the rock.
- A plant is planted in the same spot every year and slowly breaks up the soil.
- Acid rain slowly breaks down the structure of a building.
Answer:
D. Both occur between objects independently whether they are in contact or not.
Explanation:
- The gravitational force is a force that is exerted between two (or more) objects having mass. This force is always attractive and its magnitude is given by
where G is the gravitational constant, m1 and m2 are the two masses, and r is the distance between the two masses.
- The electrical force is a force that is exerted between two (or more) objects having electrical charge. It can be either attractive or repulsive, depending on the sign of the two charges, and its magnitude is given by
where k is the Coulomb's constant, q1 and q2 are the two charges, and r the distance between the two charges.
Looking at both formulas, we see that the two forces are present even when the two objects are not in contact with each other (in fact, r can assume any value in the formula). They are said to be non-contact forces. Therefore, the correct option is
D. Both occur between objects independently whether they are in contact or not.