Physics Answers

1. An elevator cab that weighs 27.8 kN moves upward. What is the tension in the cable if the cab’s speed is ___.

Find the mass of the elevator:

a. At rest

b. Uniform motion

c. Increasing at a rate of 1.2m/s2

d. Decreasing at the rate of 1.2m/s2

Please give me a solution and formula by letters. Thank you!

A 2.5 KG MASS AND A 4 KG MASS ARE ATTACHED TO A LIGHT

WEIGHT CORD THAT PASSES OVER A FRICTIONLESS PULLEY. THE

HANGING MASSES ARE LEFT FREE TO MOVE. FIND THE

A 5000 KG TRUCK IS RUNNING AT 72 KPH.

a. ) IF IT IS TO BE STOPPED BY A CONSTANT RETARDING

FORCE IN 10 S. WHAT IS THE DECELERATION ?

b ) WHAT IS THE RETARDING FORCE ?

A particle moves in a straight line such that its displacement, x meters, from a fixed point O on the line at time t seconds is given by 𝑥 = 40[𝑒 −2𝑡 − 𝑒 −4𝑡 ].

(a) Find the time when the particle is instantaneously at rest.

(b) Find the displacement of the particle from O when t = 3 s.

(c) Find the total distance travelled during the first 3 seconds of its motion

 Two bodies A and B in figure are separated by a spring. Their motion down the incline is resisted by a force P = 800 N . The coefficient of kinetic friction is 0.30 under A and 0.10 under under B. a.) compute the acceleration of block A b.) Compute the acceleration of block B c.) Determine the force in the spring. *

 An elevator weighing 12 kN starts from rest and acquires an upward velocity of 2 m/sec in a distance of 5 m. If the acceleration is constant, what is the tension in the cable? *

An automobile starting from the rest speeds up to 15 m/sec. with a constant acceleration of 1.2 m/sec^2 , runs at fast speed for sometime and finally comes to the rest with the deceleration of 1.5 m/sec ^2 . If the total distance travelled is 400 m find the total time required. *

The acceleration of a point is a= 30t m/s^2. When t= 0, s=50 m, and V= 15 m/s. a.)What is the position of the point at t=3 sec? b.) What is the velocity of the point at t= 3 sec? c.) What is the acceleration of the point at t= 3 sec? *

 A feather is dropped on the moon from a height of 1.40 meters. The acceleration of gravity on the moon is 1.67 m/s^2. Determine the time for the feather to fall to the surface of the moon. *

A triode passes a plate current of 5mA at plate voltage 150V and grid voltage of -2V. If the grid voltage is changed to -35V, the plate current drops to 3.2mA but can be restored to 5mA by increasing plate voltage to 195V. Calculate

(1) mutual conductance

(2) a.c. plate resistance

(3) amplification factor