Why do you fall in the forward direction when a moving bus brakes to a stop and fall backwards when it accelerates from rest?
When a moving bus stops suddenly, the passengers are jerked forward because of inertia the passengers tend to remain in their state of motion even though the bus has come to rest and we fall backwards when bus starts suddenly from rest because of inertia, passengers tend to remain in state of rest though bus starts moving. Hence, the passenger tends to fall backwards when the bus accelerates forward.
Popular Questions of Class 9 Science
- Q:-
Abdul, while driving to school, computes the average speed for his trip to be 20 km h-1. On his return trip along the same route, there is less traffic and the average speed is 40 km h-1. What is the average speed for Abdul’s trip?
- Q:-
Fig 8.11 shows the distance-time graph of three objects A,B and C. Study the graph and answer the following questions:
Fig. 8.11
(a) Which of the three is travelling the fastest?
(b) Are all three ever at the same point on the road?
(c) How far has C travelled when B passes A?
(d) How far has B travelled by the time it passes C? - Q:-
Two objects of masses 100 g and 200 g are moving along the same line and direction with velocities of 2 m s-1 and 1 m s-1, respectively. They collide and after the collision, the first object moves at a velocity of 1.67 m s-1. Determine the velocity of the second object.
- Q:-
The speed-time graph for a car is shown is Fig. 8.12.
Fig. 8.12
(a) Find how far does the car travel in the first 4 seconds. Shade the area on the graph that represents the distance travelled by the car during the period.
(b) Which part of the graph represents uniform motion of the car? - Q:-
Two objects, each of mass 1.5 kg, are moving in the same straight line but in opposite directions. The velocity of each object is 2.5 m s-1 before the collision during which they stick together. What will be the velocity of the combined object after collision?
- Q:-
How do poriferan animals differ from coelenterate animals?
- Q:-
Why is the weight of an object on the moon 1/6th its weight on the earth?
- Q:-
Convert into mole.
(a) 12 g of oxygen gas
(b) 20 g of water
(c) 22 g of carbon dioxide. - Q:-
From a rifle of mass 4 kg, a bullet of mass 50 g is fired with an initial velocity of 35 m s-1. Calculate the initial recoil velocity of the rifle.
- Q:-
Name the technique to separate
(i) butter from curd,
(ii) salt from sea-water,
(iii) camphor from salt.
Recently Viewed Questions of Class 9 Science
- Q:-
Why is it advised to tie any luggage kept on the roof of a bus with a rope?
- Q:-
Name the technique to separate
(i) butter from curd,
(ii) salt from sea-water,
(iii) camphor from salt. - Q:-
An object has moved through a distance. Can it have zero displacement? If yes, support your answer with an example.
- Q:-
Two objects, each of mass 1.5 kg, are moving in the same straight line but in opposite directions. The velocity of each object is 2.5 m s-1 before the collision during which they stick together. What will be the velocity of the combined object after collision?
- Q:-
A motorcar of mass 1200 kg is moving along a straight line with a uniform velocity of 90 km/h. Its velocity is slowed down to 18 km/h in 4 s by an unbalanced external force. Calculate the acceleration and change in momentum. Also calculate the magnitude of the force required.
- Q:-
How do storage grain losses occur?
- Q:-
From a rifle of mass 4 kg, a bullet of mass 50 g is fired with an initial velocity of 35 m s-1. Calculate the initial recoil velocity of the rifle.
- Q:-
Explain any one method of crop production which ensures high yield.
- Q:-
Distinguish between speed and velocity.
- Q:-
A hammer of mass 500 g, moving at 50 m s-1, strikes a nail. The nail stops the hammer in a very short time of 0.01 s. What is the force of the nail on the hammer?
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