The Space Shuttle orbits 300 km above the Earth's surface. If the Earth's radius is 6400 km, what is the gravitational acceleration experienced by the Space Shuttle while in this orbit?
Inside a discharge tube producing cathode rays, a freely rotatable wheel is mounted. When cathode rays fall on it the wheel starts rotating. What does this experiment indicate about cathode rays?
A copper ring hangs vertically from a thread with its axis along the axis of a coil as shown in the diagram.
Which statement, according to the BCS theory of superconductivity, is correct?
At room temperature, what is the current in an intrinsic semiconductor due to?
Astronauts on a long space journey are playing golf inside their spaceship, which is travelling away from the Earth with speed 0.6 c . One of the astronauts hits a drive exactly along the length of the spaceship (in its direction of travel) at speed 0.1 c in the frame of the spaceship. What is the speed of the golf ball as observed from Earth?
A ball is projected horizontally with a speed of 40 ms-1 from the top of a cliff on the surface of the Earth. What will be its approximate speed 3.0 s later if there were no air resistance?
The gravitational potential energy of two masses at a distance 2.0 m apart is - 8.0 J. What external work must be done on this system to separate the masses to a distance of 4.0 m?
A person stands on a scale in an elevator. He notices that the scale reading is lower than his normal ‘weight’. Which of the following could possibly describe the motion of the elevator?
The following is a list of some possible properties of high temperature superconductors. Some may be incorrect.
The minimum initial velocity required by a space probe to just escape the gravitational pull of a planet is called escape velocity. Which of the following quantities does NOT affect the magnitude of the escape velocity?
A simple DC motor has n turns of wire in the armature and has an area of A m2. A current of I amperes passes through the armature. The plane of the armature is at 0 o to the direction of the magnetic field of strength B Teslas. What is the torque on the armature if the area and the current are doubled and the armature is at an angle of 60 o to the magnetic field direction?
A current flows in a straight wire placed perpendicular to a uniform magnetic field. The current varies with time as shown on the diagram below.
William Bragg and his son Lawrence studied crystals and Lawrence determined the mathematical formula:
A straight current-carrying conductor is placed within an external magnetic field as shown below.