Advertisements
Advertisements
Question
A car of mass 800 kg, moving at 54 kmh−1 is brought to rest over a distance of 15 m. Find the retarding force developed by the brakes of the car.
Solution
Mass of car = m = 800 kg
Initial velocity of car = u – 54 kmh−1
u = `54xx5/18` ms−1 = 15 ms−1
Final velocity of car = v = 0
Distance covered = S = 15 m
Retarding force = F = ?
v2 – w2 = 2a S
(0)2 − (15)2 = 2a(15)
30 a = −225
a = `-225/30`
a = −7.5 ms−2
F = ma = (800) (−7.5)
F = −6000N
APPEARS IN
RELATED QUESTIONS
The north pole of a magnet ______ the north pole of another magnet.
Make a match
| A group | B group |
| 1. Fluid | a. Higher pressure |
| 2. Blunt knife | b. Atmospheric pressure |
| 3. sharp needle | c. Specific gravity |
| 4. Relative density | d. Lower pressure |
| 5. Hecto pascal | e. Same pressure in all directions |
A ball is hanging by string from the ceiling of the roof. Draw a neat labelled diagram showing the forces acting on the ball and the string.
A spring is compressed against a rigid wall. Draw a neat and labeled diagram showing the forces acting on the spring.
Name the physical quantity that causes motion in a body.
A golfer hits a ball at rest, such that the contact between the ball and golf stick is for 0.1 s. If the golf ball covers a linear distance of 400 m in 2 s, find the magnitude of force applied. Mass of golf ball is 50 g.
Gravitational force is a ______ force.
The water sprinkler used for grass lawns begins to rotate as soon as the water is supplied. Explain the principle on which it works.
In the circuit shown in figure, when the key is closed, the compass needle placed in the match box deflects. Name the force which cases this deflection.
Does the force of gravity act on dust particles?
