Answer:
Friction produces unnecessary heat leading to the wastage of energy. The force of friction acts in the opposite direction of motion, so friction slows down the motion of moving objects. Forest fires are caused due to the friction between tree branches. However, friction can also cause problems in a car. Friction between moving engine parts increases their temperature and causes the parts to wear down. Friction can be both harmful and helpful, so it may be necessary to decrease or increase friction.
Answer:
Shawn's kinetic energy is 61.45 J.
Explanation:
Given;
Mass of the system is, 
Displacement of the bike is, 
Time taken is, 
Let the constant velocity be 
.
For constant velocity, magnitude of velocity is given as distance by time.
Therefore, 
Now, kinetic energy of a body is given as:
Here, 
Therefore, Shawn's kinetic energy is 61.45 J.
To calculate the volume of a rectangular, we have to multiply the value of height, length and width.
8x5x4 = 160 cm ^3
Answer: When rubbing a balloon with a wool cloth, it puts negative charges on the balloon. Negative charges attract to positive charges. If a balloon is not rubbed with the wool cloth, it has an equal amount of negative to positive charges, so it will attract to a rubbed balloon.
Answer;
=15855.40 kg/m^3
Explanation;
Volume (V) of the cylinder = pi x r^2 x h
V = 3.14 x (44/2 x 10^-3)^2 x 41.5 x 10^-3
V = 6.307 x 10^-5 m^3
By density = m/V
mass = 1 kg
density = 1/(6.307 x 10^-5) = 15855.40 kg/m^3
