Acceleration for class 9th (lec 7)

video lectures for Acceleration

 

Question 1:  A body with an initial velocity of `3 ms^{-1}` moves with an acceleration of `2 ms^{-1}` Then the distance traveled in the 4th second is _________ `m`. 

 

(a) `10`  

(b) `6`  

(c) `7`  

(d) `28`

Question 2: The driver of a `TGV` travelling at a speed of `90 ms^{-1}` sights a truck on the rail track at a distance of `1 km` ahead. Then he applies the brakes to decelerate the train at the rate of `5 ms^{-1}`. What is the distance travelled by the train before coming to rest? Will the train collide with the truck? 

a) `180 m`

b) `160 m`

c) `810 m`

d) `8100 m`

Question 3: A body is projected vertically upward. If its velocity after `2 s` is `25 ms^{-1}`, find the velocity of projection. (Take `g` = `10 ms^{-1}`) 

a) `25 ms^{-1}`

b) `20 ms^{-1}`

c) `40 ms^{-1}`

d) `45 ms^{-1}`

Question 4: What is the acceleration of a body when the velocity remains constant?

a) minimum

b) maximum

c) zero

d) Nun of these

Question 5: A particle in one-dimensional motion, moving with constant velocity must have ________ acceleration.

a) zero

b) maximum

c) minimum

d) none of above

Question 6: A freely falling body travels with ______________.

a) non-uniform acceleration 

b) uniform acceleration

c) zero acceleration

d) none of above

Question 7: A body is dropped from the top of a tower. Simultaneously, another body is projected vertically up from the tower. If they meet with equal speed `V`, then initial velocity of the body projected upwards is:

a) `V`

b) `\frac{V}{2}`

c) `\frac{V}{\sqrt{2}}`

d) `\sqrt{2}V`

Question 8: If a body starts from rest and moves with uniform

acceleration, then

a)  `v ∝ t`  

b) `s ∝ t`

c) `v ∝ s`

d) `s ∝ t`

Question 9: The speed of a bus decreases from `80 kmh^{-1}` to `60 kmh^{-1}` in 5sec. Find the acceleration of the bus.

a) `2 ms^{-2}`

b) `2 ms^{-1}`

c) `1.1 ms^{-2}`

d) `-1.1 ms^{-2}`

Question 10: A train starts from a station and attains a speed of `40 kmh^{-1}` in `10 min.` while moving with uniform acceleration. Find its acceleration.

a) `0.018 s^{-2}`

b) `0.8 s^{-2}`

c) `0.08 s^{2}`

d) `0.018 s`

Question 11: A train is moving with a speed of `90 kmh^{-1}`. it produces a uniform acceleration of `-0.5 ms^{-1}` when brakes are applied. How much distance will the train cover before coming to rest?

a) `540 m`

b) `450 m`

c) `-625 m`

d) `625 m`

Question 12: A trolley is going down an inclined plane with an acceleration of `2ms^{-1}`. What will be its velocity after `3s` of starting the motoin?

a) `1.6 ms^{-1}`

b) `0.06 ms^{-1}`

c) `6 ms^{-1}`

d) `0.6 ms^{-1}`

Question 13: A racing car has a uniform acceleration of `4 ms`. What is the distance it will cover `10 s ` after starting the motion?

a) `1600 m`

b) `100 m`

c)  `200 m`

d)  `800 m`

Question 14: A stone is thrown vertically upward with a velocity of `5 ms^{-1}`. If the given acclatrion towards the stone during the motion is `10 ms^{-2}`, then what is the height attained by the stone in how much time will it take to reach there?

a) `1.5s`

b) `5s`

c) `1s`

d) `0.5s`

Question 15: If a body is projected vertically upwards, then on reaching maximum height, its

a)  velocity is zero and acceleration is not zero.

b)  velocity is not zero and acceleration is zero.

c)  both velocity and acceleration are not zero.

d)  both velocity and acceleration are zero.

Question 16: By applyind the break, the car slowed down by `6ms^{-1}`. If the takes `2s` to stop when the brakes are applied, then find the distance covered by the car during this time.

a) `36 m`

b) `6 m`

c) `24 m`

d) `12 m`

Question 17: When brakes are applied, the velocity of a car changes from `40 ms^{-1}` to `10 ms^{-1}` in `10 s`. The acceleration produced in it is

a) `3 ms^{-2}`

b) `-3 ms^{-2}`

c) `5 ms^{-2}`

d) `-5 ms^{-2}`

Question 18: A body with an initial velocity of `3 ms^{-1}` moves with an acceleration of `2 ms^{-2}`. Then the distance traveled in the `4th` second is

a) `10 m`

b) `6 m`

c) `7 m`

d) `28 m`

Answer key

Q1 (a), Q2 (c), Q3 (d), Q4 (c), Q5 (a), Q6 (b), Q7 (d), Q8 (a), Q9 (d), Q10 (a), Q11 (d), Q12 (d), Q13 (c), Q14 (d), Q15 (a), Q16 (d), Q17 (b), Q18 (a)