Answer:

Explanation:
given,
Speed of sound = 343 m/s
frequency of horn = 260 Hz
the friend is approaching, the frequency is increased by the Doppler Effect. The frequency is 266 Hz
using formula





the speed of friends approaching is equal to 
Answer:
<h3>130N</h3>
Explanation:
according to Newtons second law;
F = ma
F = m(v-u)/t
m is the mass = 60+5 = 65kg
v is the final velocity = 0m/s
initial velocity = 8m/s
time t = 4.0s
F = 65(8)/4
F = 65*2
F = 130N
Hence he applied a force of 130N
Answer:
Newton's third law of motion is naturally applied to collisions between two objects. In a collision between two objects, both objects experience forces that are equal in magnitude and opposite in direction. Such forces often cause one object to speed up (gain momentum) and the other object to slow down (lose momentum).
Well, first off, mechanical energy is the sum of kinetic and potential energy in an object that is used to do work. In other words, it is energy in an object due to its motion or position, or both. Heat energy is the result of the movement of tiny particles called atoms, molecules or ions in solids, liquids and gases. Light energy is the only form of energy that we can actually see directly. It is formed through chemical, radiation, and mechanical means. Striking a match stick (mechanical energy) creates fire, which has a ton of heat energy, and produces light too, so the answer, is A. I hope i could help!
That is true. But you still should to the book given to you to find the right answer