Physics Answers

1. Which of the following describes the speed of light according to the Special Relativity Theory?

A The speed of light is constant.

B. The light speed depends on the speed of the observer.

C The speed of light depends on the source.

D. The speed of light is infinite

2. One of two identical twins became an astronaut, while the other worked at PAGASA. The astronaut had a journey to a nearby star and has been gone for several years. Upon the astronauts return, the twins reunite and observe their physical appearances. The result will be that

A. The astronaut has aged less

B. The one working in PAGASA has aged less

C. Both have aged the same

D. None of the above

3 A man on the ground sees a rocket moving past him at 99% the speed of light. Compared to when the rocket is at rest, the man measures the length as:

A. Longer

B. Shorter

C. The same length

D. None of the above

A unit vector normal to the surface z=x^2+y^2

At the point (1,2,5) is

A=yz then it's gradient is

A battery has an emf of 1.50V. If you short circuit the battery with a wire with resistance 8.0Ω, a voltage of 1.12V is measured across the battery. What is the internal resistance of the battery?

A wire with length 15m and diameter 1mm has resistance 0.28Ω. What is the material this wire is made of?

A copper wire having length L and diameter d has risistance R. What will the resistance be of a copper wire with length 2L and diameter 2d?

A block with mass M is at rest on a frictionless, horizontal surface. The block is attached to an ideal, massless spring that initially is in equilibrium.

A riffle bullet with mass m_p is fired with speed v_b​ into the block and embeds itself in the block. The impact compresses the spring over a distance D. The block and bullet oscillate in simple harmonic motion.

(a) Calculate the angular frequency ω of the oscillation.

(b) When time t=0 is defined as the instant of impact, the positive x-axis is pointing to the right, and x=0 is the initial position of the block before impact, give an expression x(t) for the time dependent position of the block and bullet. Assume that the impact itself takes no time.

Show on the dimensional Analysis that v^2 - u^2 = 2as where u initial velocity, v is the final velocity, a is the acceleration of the body and s is the distance moved

Show on the dimensional Analysis that v^2 - u^2 = 2as

Show on the dimensional Analysis that v^2 - u^2 = 2as where u is the initial velocity, v is the final velocity, a is the acceleration due to gravity and s is the distance moved