1) It's B. Ultraviolet rays cause substances to fluoresce.
2) It's D. The lens enlarges the image.
3) It's actually more powerful so it's B. People usually buy products based on quality than portability.
4) CORRECT
5) CORRECT
Answer:
v₁ = 1 [m/s].
Explanation:
This problem can be solved by using the principle of conservation of linear momentum. Where momentum is conserved before and after catching the snowball.
where:
P = linear momentum [kg*m/s]
m = mass [kg]
v = velocity [m/s]
As the momentum is conserved, it will be the same as that received by the person who catches the snowball.
That is, the person who catches the snowball moves backwards with a speed of 1 [m/s].
Answer:
The total mechanical energy of a pendulum is conserved neglecting the friction.
Explanation:
- When a simple pendulum swings back and forth, it has some energy associated with its motion.
- The total energy of a simple pendulum in harmonic motion at any instant of time is equal to the sum of the potential and kinetic energy.
- The potential energy of the simple pendulum is given by P.E = mgh
- The kinetic energy of the simple pendulum is given by, K.E = 1/2mv²
- When the pendulum swings to one end, its velocity equals zero temporarily where the potential energy becomes maximum.
- When the pendulum reaches the vertical line, its velocity and kinetic energy become maximum.
- Hence, the total mechanical energy of a pendulum as it swings back and forth is conserved neglecting the resistance.
A glass of salt water will take a slightly longer time & slightly lower temperature (28 F as compared to 32 F for fresh water) to freeze than a glass of fresh water.
Hope this helps!