Physics Answers

THE SPEED OF 5 KG BODY IS TO BE INCREASED FROM 10

M/S TO 20 M/S. WHAT CONSTANT FORCE IS NEEDED TO

PRODUCE THIS CHANGE IN SPEED IN EXACTLY 5 S ?

A rocket of mass 4×10⁴ kg, when full with fuel at launching pad, it's fired vertically upward and a burnout mass of 2×10⁴kg gases are exhausted at the rate of 20 slugs/second, with a velocity of 6×10³ m/s relative to the rocket (exhaust velocity) both quantities are assumed to be constant while the fuel is burning, what's the thrust, neglecting all external forces, what would be the speed of the rocket at burnout?

A car’s tachometer indicates the angular velocity of the engine’s crankshaft in rpm. A car stopped

at a traffic light has its engine idling at 500 rpm. When the light turns green, the crankshaft

rotation speeds up at a constant rate to 2500 rpm in a time interval of 3.0 s. How many

revolutions does the crankshaft make in these time interval?

. A 50 kg mass is sitting on a frictionless surface. An unknown constant force pushes the mass for

2 seconds until the mass reaches a velocity of 3 m/s

a. What is the initial momentum of the mass?

b. What is the final momentum of the mass?

c. What was the force acting on the mass?

d. What was the impulse acting on the mass?

A 12N bag is hanging with a cord. How much is the least tension exerted by the cord to stay the bag at rest?

a.    1.2N                                             c. 2.1N

b.    21.8N                                           d. 12N

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

a.    Increasing at a rate of 1.2m/s²     

b.    Decreasing at the rate of 1.2m/s²

1. A rock is dropped from a height of 1.6 meters. How fast is the rock falling just before it hits the ground?

Determine the lateral magnification of an object with a distance equal to 186 cm if the image’s distance is observed to be equal to 27.4 cm, considering that both are relative from the vertex.

2. What is the image description of a 3 cm tall pen light when placed at distance of 30.5 cm, from a converging lens having a focal length of 10.2 cm?

how did the size of the current in the coil affect the strength of the electromagnet