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- Question
What is a Contact Force and explain with an example?
- Correct Answer
- A Contact force is a force applied to a body by another body that is in contact with it Contact force acts on a point of direct contact between the two objects This force can either be continuous as a continuous force or can be momentary in the form of an impulse Contact force is governed by Newton?s Laws Examples :: Contact force is responsible for most of the interactions we experience in the daily life 1 Writing your name with a pen, pushing a car up a hill, lifting an object, etc 2 Kicking a ball, hammering a nail, etc are some of the everyday examples where contact forces are at work In the first case, the force is continuously applied by the person on the car or pen or an object while in the second case the force is delivered in a short impulse Contact forces are often decomposed into orthogonal components one perpendicular to the surface in contact called the normal force, and one parallel to the surface in contact, called the friction force
- 1. The capacity of a water heater is measured in
Options- A. Gallons
- B. Liters
- C. Meters
- D. Both A & B Discuss
- 2. When a ray of light is refracted by a prism such that the angle of deviation is minimum then
Options- A. the angle of emergence is equal to the angle of incidence
- B. the angle of emergence is greater than the angle of incidence
- C. the angle of emergence is smaller than the angle of incidence
- D. the sum of the angle of incidence and the angle of emergence is equal to 90 degrees Discuss
- 3. When two similar sources vibrate with slightly different frequencies , a regular rise and fall occurs in the loudness of tone. This phenomenon is known as
Options- A. doppler effect
- B. beats
- C. resonance
- D. echo Discuss
- 4. A stone floor feels cold to the bare feet but a carpet on the same floor feels warm. This is because
Options- A. the floor and carpet are at different temperatures
- B. the stone conveys the heat away from the feet more rapidly than the carpet
- C. the carpet is a better conductor of heat than the stone
- D. the human body maintains a constant temperature Discuss
- 5. A cup of hot coffee is placed on a metal table in a room. By which of the following methods does it lose heat?
Options- A. conduction and convection only
- B. conduction and radiation only
- C. convection and radiation only
- D. conduction, convection and radiation Discuss
- 6. RADAR is used for
Options- A. detecting and locating the position of objects such as Aeroplanes
- B. locating submerged submarines
- C. locating geostationary satellites
- D. receiving a signals in a radio receiver Discuss
- 7. Which color has the highest frequency?
Options- A. Violet
- B. Red
- C. Indigo
- D. Green Discuss
- 8. The Ankle is a third-class lever.
Options- A. TRUE
- B. FALSE Discuss
- 9. Which of the following is the best conductor of electricity?
Options- A. Aluminium
- B. Gold
- C. Silver
- D. Copper Discuss
- 10. Which of the following properties is found only in ferromagnetic materials ?
Options- A. Susceptibility independent of temperature
- B. Point in a particular direction
- C. Hysteresis
- D. Attracting a magnetic substance Discuss
Physics problems
Search Results
Correct Answer: Both A & B
Explanation:
The capacity of a water heater is measured in Gallons or Liters. In the USA, it is measured in Gallons and in India, we measure it in Liters.
Hence, if the capacity of the water heater is 15 gallons or 15 liters, then it says that it can hold 15 gallons or 15 liters of water.
Correct Answer: the angle of emergence is equal to the angle of incidence
Correct Answer: beats
Explanation:
Beats means the periodic increase and decrease in loudness heard when two notes of nearly the same frequency are sounded simultaneously.
Correct Answer: the stone conveys the heat away from the feet more rapidly than the carpet
Explanation:
Both the floor and the carpet have the same temperature as both are exposed to the same atmosphere. But the former conducts away the heat from the feet better than the carpet as the latter is a non-conductor. So the feet losing more heat, the floor appears cooler to the feet.
Correct Answer: conduction, convection and radiation
Explanation:
Part of the heat is conducted away by the metal table. Convection currents in air near the surface of the coffee are set up which accounts for some heat loss. Heat is also lost by radiation from the hot coffee to the surroundings. Most of the heat is lost by the last method.
Correct Answer: detecting and locating the position of objects such as Aeroplanes
Explanation:
RADAR - RAdio Detection And Ranging.
A radar system consists of a transmitter producing electromagnetic waves in the radio or microwaves domain, a transmitting antenna, a receiving antenna (often the same antenna is used for transmitting and receiving) and a receiver and processor to determine properties of the objects.
Radar is an object-detection system that uses radio waves to determine the range, angle, or velocity of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain.
Radio waves from the transmitter reflect off the object and return to the receiver, giving information about the object's location and speed.
Correct Answer: Violet
Explanation:
In VIBGYOR. It has colors ordered from highest to lowest frequency.
Violet > Indigo > Blue > Green > Yellow > Orange > Red
That says Violet has the highest frequency.
We know, Speed of light = Frequency x Wavelength
=> As frequeny is inversely proportional to wavelength i.e, as frequwncy goes high wavelength goes down.
So, the violet color has the highest frequency.
Correct Answer: FALSE
Explanation:
False. The ankle is not the third-class lever in the body.
Levers are typically labeled as first class, second class, or third class. All three types are found in the body, but most levers in the human body are third class.
First-class levers in the human body are rare and have the axis (fulcrum) located between the weight (resistance) and the force. One example is the joint between the head and the first vertebra.
In a second-class lever, the weight (resistance) is located between the axis (fulcrum) and the force. An example of a second-class lever in the human body is found in the lower leg when someone stands on tiptoes
In a third-class lever, the most common in the human body, force is applied between the resistance (weight) and the axis (fulcrum). There are numerous third-class levers in the human body; one example can be illustrated in the elbow joint.
Correct Answer: Silver
Explanation:
silver is the best conductor of electricity.
When compared to remaining 3 metals, as Silver having more number of free electrons in its valency shell it is the good conductor of electricity.
Conductors Thermal Conductivity @ 25degree C
Silver --- 429
Copper --- 401
Gold --- 310
Aluminium --- 250
Correct Answer: Hysteresis
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