A 4.0-kg mass on the end of a string rotates in a circular motion on a horizontal frictionless table. The mass has a constant speed of 2.0 m/s and the radius of the circle is 0.80 m. What is the magnitude of the resultant force acting on the mass?
A. 39 N
B. 20 N
C. 44 N
D. 0 N
E. 30 N
Answer: B
You might also like to view...
Hydrogen gas seems to have a diffusivity of about 2.6 x 10^-13 m^2/s when diffusing into iron at 770 K. What would you expect the rate of diffusion or mass flow rate per unit area of hydrogen to be when stored in an iron container at 5 atmospheres pressure, assuming the density of hydrogen at 1 mm in the iron from the containing surface to be 5% of the normal hydrogen density, given by p/RT?
What will be an ideal response?
Which statement is true?
A) If we could build a spaceship capable of traveling at a speed near the speed of light, passengers on the ship could make a journey to a star that is 500 light-years away within their lifetimes. B) If we could build a spaceship capable of traveling at a speed near the speed of light, we could send a ship to a star that is 500 light-years away and it would return just a few years after we launched it. C) Thanks to effects of special relativity, we could build a spaceship that could go close to the speed of light with much less fuel than we would have guessed from Newton's laws of motion. D) Because special relativity tells us that we cannot reach or exceed the speed of light, it means that distant stars will never be within our reach because the time required to reach them will always be quite long, even with fast spaceships.
In a 35 mm single lens reflex camera (SLR) the distance from the lens to the film is varied in order to focus on objects at varying distances
Over what range must a lens of 45 mm focal length vary if the camera is to be able to focus on objects ranging in distance from infinity down to 1.4 m from the camera? A) 1.49 mm B) 1.20 mm C) 4.48 mm D) 5.98 mm E) 2.09 mm
Two equal positive charges are separated by d. Then one of the charges is replaced by a negative charge of the same magnitude. Take the potential at infinity to be zero. In which situation is the potential higher midway between the charges; is this value of potential zero?
a. the first situation; no c. the second situation; no b. the first situation; yes d. the second situation; yes