Accelaration

Q.

The cheetah is the fastest land animal and can achieve a peak velocity of 100 km/h up to the distances less than 500 m. If a cheetah spots his prey at a distance of 100 m, what is the minimum time it will take to get its prey, if the average velocity attained by it is 90 km/h?

Q. Question 13
A person holds a bundle of hay over his head for 30 minutes and gets tired. Has he done some work or not? Justify your answer.

Q.

A bus decreases its speed from 80km/hr to 60 km/hr in 5 sec. Find the acceleration of the bus.

1. 2.11 m/s²

2. 1.11 m/s²

3. 2.22m/s²

4. 0 m/s²

Q. A particle had a velocity of $18m/s$ in the right direction and $2.4s$ later its velocity was $30m/s$ in the opposite direction. What was the acceleration of the particle during this $2.4s$ interval?

1. $-5m/s^2$
2. $-10m/s^2$
3. $-15m/s^2$
4. $-20m/s^2$

Q.

Why is it dangerous to jump out of a moving vehicle? How can the danger be minimised? Explain.

Q.

The distance between two places A and B is $180km$ by road and $120km$ by air. An airplane takes $20min$to go from A to B whereas a deluxe bus starting at A takes $5h$ to reach B. Find the average speed and average velocity by both means of transport. (Ignore the vertical ascent of the airplane).

Q.

Ann jogs from one end A to the other end B of a straight 300 m road in 2 minutes 50 seconds. She then turns around and jogs 100 m back to point C in another 1 minute. What are Ann's average speeds and velocities in jogging from A to B and from A to C?

1. A to B-
   Speed: 1.76 m/s
   Velocity: 1.76 m/s
   B to C-
   Speed: 1.74 m/s
   Velocity: 0.869 m/s
2. A to B-
   Speed: 0.869m/s
   Velocity: 1.76m/s
   B to C-
   Speed: 1.74m/s
   Velocity: 0
3. A to B-
   Speed: 1.76m/s
   Velocity: 0.869m/s
   B to C-
   Speed: 0
   Velocity: 1.74m/s
4. A to B-
   Speed: 0.869m/s
   Velocity: 1.76m/s
   B to C-
   Speed: 1.74m/s
   Velocity: 1.74 m/s

Q. A police car moving at $60m{s}^{-1}$ is pursuing a minivan moving at $45m{s}^{-1}$. How long will it take the police car to catch up if the mini-van is $600m$ ahead of the police car at the beginning of the chase?

1. $15\text{second}$
2. $50\text{second}$
3. $10\text{second}$
4. $40\text{second}$

Q. A cyclist speed up at a constant rate from rest to $8m/s$ in $6s$. Find the acceleration of the cyclist.

1. $\frac{1}{3}m/s^2$
2. $\frac{4}{3}m/s^2$
3. $\frac{2}{3}m/s^2$
4. $\frac{3}{4}m/s^2$

Q.

When is the work done positive and negative?

Q.

A force acts in the direction of motion of the object. During this interval the kinetic energy of the body changes from $25J$ to $100J$. The work done by the force is

1. 75 J

2. 0 J

3. 25 J

4. 100 J

Q.

If the speed of a moving object A is $am{s}^{-1}$ and its velocity is $bm{s}^{-1}$, what is the similarity you observe?

Q. A bus decreases its speed from $80km/hr$ to $60km/hr$ on a straight road in $5sec$. Find the magnitude of acceleration of the bus.

1. 2.22m/s²

2. 2.11 m/s²

3. 1.11 m/s²

4. 0 m/s²

Q.

Fastening of seat belts is advised for the safety of persons sitting in a moving car. Give reason.

Q. A trolley with load on it is moving on a flat plane. The force felt by the trolley due to the load is $F$. What is the work done by this force if the trolley moves a distance $d$?

1. $Fd$
2. $-Fd$
3. $0$
4. $Fd/2$

Q. A car increases its speed from $20km/hr$ to $30km/hr$ in $10seconds.$ Its acceleration is

1. $30m/s^2$
2. $3m/s^2$
3. $18m/s^2$
4. $0.2778m/s^2$

Q.

A car decreases its speed from $80km/h$ to $60km/h$ is $5seconds$. The acceleration of the car is :

1. 1.12 m/s²

2. -1.11 m/s²

3. -1.14 m/s²

4. 1.11 m/s²

Q.

Define inertia with respect to motion.

Q.

A car takes 4 hrs to travel from Bangalore to Chennai whereas the flight takes only 30 min to travel from Bangalore to Chennai. The distance from Bangalore to Chennai by road is 400 km and by air is 150 km. Assume flight path to be straight.

Answer in the given order (in $kmh{r}^{-1}$):

Find the average speed of flight, average velocity of flight, average speed of car, average velocity of car.

1. 300 , 300, 37.5 , 100

2. 300 , 37.5, 100 , 100

3. 300, 300, 200, 100

4. 300, 300, 100, 37.5

Q. A car decreases its speed from $80kmh{r}^{-1}$ to $60kmh{r}^{-1}$ in $5$ seconds. The acceleration of the car is:

1. $-1.62m{s}^{-2}$
2. $-1.11m{s}^{-2}$
3. $1.62m{s}^{-2}$
4. $1.11m{s}^{-2}$

Q. Consider the following statements.
A. Air has the capacity to do work.
B. Air exerts pressure

1. Both A and B are correct
2. A is correct and B is incorrect
3. A is incorrect and B is correct
4. Both A and B are incorrect

Q. Choose the correct statement.

1. The average velocity of a moving body can be zero.
2. The average velocity of a moving body cannot be zero.
3. The average speed of a moving body can be zero.
4. The average speed of a moving body is always less than the average velocity.

Q.

Choose the correct option regarding Inertia:

1. Only bodies at rest, resists the change in their state of motion.

2. Inertia is the tendency of undisturbed objects to stay at rest or to keep moving with the same velocity.

3. Both B and C

4. Inertia is confined only to the objects in motion.

Q. A train accelerates from rest to a speed $v$ in time $t$. What is the acceleration of a boy sitting in the train as seen from his father sitting on the opposite seat?

1. $\frac{v}{t}$
2. 0
3. $\frac{-v}{t}$
4. $\frac{2v}{t}$

Q. Acceleration is defined as the rate of change of velocity.

1. False
2. True

Q. An insect moves along the sides of a wall of dimension $12m\times 5m$, starting from one corner and reaches the diagonally opposite corner. If the insect takes $2s$ for its motion, then find the ratio of average speed to average velocity of insect.

1. $17:13$
2. $12:5$
3. $13:5$
4. $17:12$

Q. Which of the following is true about the value of acceleration?

1. It is always negative.
2. It is always positive.
3. It can be positive, negative, or zero.
4. It is always equal to zero.