Physics Answers

In a billiard table, a ball of mass weighing 250 g rolls with a velocity of

2.5 m/s and rebounds back at 2.5 m/s. Calculate the following:

a. change in momentum

b. impulse experienced by the ball

Let the angle be the angle that the vector makes with

the measured counterclockwise from that axis. Find

the angle for a vector that has the following components: 

(a)Ax=-6.5m, Ay=1.9m

Derive the expression of the Q = ΔE of a nuclear reaction, hence, determine the Q value and the nature of the reaction F19 (H1,α) O16( 18.998405u, 15.994915u, 4.002603u, 1.007825u are masses of F19, O16, α, H1) respectively.

a ii). Discuss the primary processes by which gamma rays interact with matter

b). The Q value of the Na23 (n,α) F20 reaction is -5.4MeV. Determine the threshold energy of the neutrons for this reaction (22.9898u, 18.9964u, 4.0039u, 1.008665u are the masses of Na23, F20 α and n respectively).

1. A merry-go-round rotates at the rate of 0.24 rev/s with an 71 kg man standing at a point 2.7 m from the axis of rotation. What is the new angular speed when the man walks to a point 1 m from the center? Consider the merry-go-round is a solid 79 kg cylinder of radius of 2.7 m
2. What is the change in kinetic energy due to this movement?

Two pans of a balance are 25.7 cm apart.

The fulcrum of the balance has been shifted

0.893 cm away from the center by a dishonest

shopkeeper.

By what percentage is the true weight of the

goods being marked up by the shopkeeper?

Assume the balance has negligible mass.

A resistance of 12 ohms an Inductance of 0.15 Henry and a capacitance of 130 f are connected in series across a supply of 200 volts 50 He. Calculate the 1.impedenace 2.the current 3.powerfactor 4.phase angle between voltage and current and 5.powerconsumed

Compute the contracted length of an

object whose initial length 30 m and travel with a velocity 0.65c?

There is a set of twins, one an

astronaut, the other works for mission control of NASA. The astronaut leaves on

a deep space trip traveling at 95% the speed of light. Upon returning the

astronauts clock has measured ten years, so the astronaut has aged 10

years. What is the time that the

earth-bound brother measures while his twin was on his exploration in space?

How old is he?

Assume that lightning strikes completely vertically and that a known current flows from the cloud into the ground for some time. We want to detect a lightning strike with the help of a coil that is connected directly to a voltmeter. Explain which phenomenon is responsible for lightning detection. Sketch the magnetic field of lightning and how the coil should be oriented for the effect to be strongest.

A polarizer and analyzer are oriented so that the amount of transmitted light is maximum. 

Through what angle should either be turned so that the intensity of transmitted light is 

reduced to (a) 0.75 and (b) 0.25 times the maximum intensity?