In an exothermic reaction, there is a transfer of energy to the surroundings in the form of heat energy. The surroundings of the reaction will experience an increase in temperature. Many types of chemical reactions are exothermic, including combustion reactions, respiration & neutralization reactions of bases & acids.
Answer:
Work done by the spring is negative
Explanation:
We can answer this question by thinking what is the force acting on the box.
In fact, the force acting on the box is the restoring force of the spring, which is given by Hooke's Law:

where
k is the spring constant
x is the displacement of the box with respect to the equilibrium position of the spring
The negative sign in the equation indicates that the direction of the force is always opposite to the direction of the displacement: so, whether the spring is compressed or stretched, the force applied by the spring on the box is towards the equilibrium position.
The work done by the restoring force is also given by

where
F is the restoring force
x is the displacement
is the angle between the direction of the force and the displacement
Here we know that the force is always opposite to the displacement, so

Which means that the work done by the spring is always negative, since the direction of the restoring force is always opposite to the direction of motion.
We know, F = k * q₁ * q₂ / r²
Substitute the known values,
F = 9 * 10⁹ * 5 * 7 / (1.2)²
F = 315 * 10⁹ / 1.44
F = 218.75 * 10⁹ N
F = 2.1875 * 10¹¹ N [ Final Answer ]
Hope this helps!
Answer:
A) Magma emplacement
Explanation:
Sedimentary structures forms during deposition of sediments. It can also form after sediments have been deposited. Sedimentary structures can only be found in sedimentary rocks. Some examples include mud cracks, ripple marks, cross stratification, potholes, etc
Magma emplacement is an igneous process which describes the different mechanisms by which magma can be emplaced. It is only typical of igneous rocks.