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An electron moving with a velocity of 5 × 10⁴ m/s enters into a uniform electric field and acquires a uniform acceleration of 104 ms^-2 in the direction of its initial motion. (i) Calculate the time in which the electron would acquire a velocity double of its initial velocity. (ii) How much distance the electron would cover in this time?

Answer: Given Initial velocity (u) = 5 × 104 m/s Acceleration (a) = 104 ms-2 (i) Calculate the time in which the electron would acquire a... View Article

Using following data, draw time – displacement graph for a moving object: Use this graph to find average velocity for first 4 s, for next 4 s and for last 6 s.

Answer: Average velocity for the first 4s = = (4 - 0)/(4 - 0) = 4/4 = 1 ms-1 Average velocity of next 4 s = v = = 0 Average velocity for... View Article

An object starting from rest travels 20 m in first 2 s and 160 m in next 4 s. What will be the velocity after 7 s from the start.

Answer: Here object starts from rest hence Initial velocity (u) = 0 t = 2s s = 20 m According to Second equation of motion s = ut + 1/2 at2 s =... View Article

An object is dropped from rest at a height of 150 m and simultaneously another object is dropped from rest at a height 100 m. What is the difference in their heights after 2 s if both the objects drop with same accelerations? How does the difference in heights vary with time?

Answer: When two objects fall with the same acceleration simultaneously, after 2 seconds the difference in their heights will not change and it... View Article

Draw a velocity versus time graph of a stone thrown vertically upwards and then coming downwards after attaining the maximum height.

Answer: The velocity versus time graph of a stone thrown upwards vertically is as given below: The meaning of velocity of an object can be... View Article

The velocity-time graph shows the motion of a cyclist. Find (i) its acceleration (ii) its velocity and (iii) the distance covered by the cyclist in 15 seconds

Answer: (i) its acceleration Acceleration is defined as the rate of change of velocity with respect to time. As velocity is constant,... View Article

A motorcyclist drives from A to B with a uniform speed of 30 km/h and returns back with a speed of 20 km h–1. Find its average speed.

Answer: Let the distance from A to B is D km. Distance for the entire journey is 2D km. Time taken to go from A to B is D/30 hr and that of B to... View Article

A car starts from rest and moves along the x-axis with constant acceleration of 5 m/s2 for 8 seconds. If it then continues with constant velocity, what distance will the car cover in 12 seconds since it started from the rest?

Answer: Car Starts from rest hence Initial velocity (u) = 0 Acceleration (a) = 5 m/s2 Time (t) = 8s v = u + at v = 0 + (5 × 8) From... View Article

A girl walks along a straight path to drop a letter in the letterbox and comes back to her initial position. Her displacement–time graph is shown in Fig. Plot a velocity-time graph for the same

Answer: Displacement of an object is defined as how far the object is from its initial point. In displacement time graph, displacement is... View Article

How will the equations of motion for an object moving with a uniform velocity change?

Answer: If object is moving with a uniform velocity then v=µ and a = 0. In this scenario equation for distance is given below. S = ut and... View Article

The displacement of a moving object in a given interval of time is zero. Would the distance travelled by the object also be zero? Justify your answer.

Answer: Displacement is defined as the change in position of an object. It is a vector quantity and has a direction and magnitude. Distance is... View Article

In which of the following cases of motions, the distance moved and the magnitude of displacement are equal? (a) If the car is moving on straight road (b) If the car is moving in circular path (c) The pendulum is moving to and fro (d) The earth is revolving around the Sun

Answer: (a) If the car is moving on straight road Displacement is defined as the change in position of an object. It is a vector quantity and has... View Article

Slope of a velocity – time graph gives (a) the distance (b) the displacement (c) the acceleration (d) the speed

Answer: (c) the acceleration Acceleration is the rate at which velocity changes over time. The slope of the velocity time graph indicates the... View Article

Which of the following figures represents uniform motion of a moving object correctly?

Answer: (a) Distance in graph (a) is uniformly increasing with time hence it represents uniform motion. Uniform motion is a type of motion is... View Article

Four cars A, B, C and D are moving on a levelled road. Their distance versus time graphs are shown in Fig. Choose the correct statement (a) Car A is faster than car D. (b) Car B is the slowest. (c) Car D is faster than car C. (d) Car C is the slowest.

Answer: (b) Car B is the slowest. Graph shows that Car B covers less distance in a given time than A, C and D cars hence it is the slowest.... View Article

Area under a v – t graph represents a physical quantity which has the unit (a) m2 (b) m (c) m3 (d) m s–1

Answer: (b) m The area under the v-t graph represents displacement in metres (m). Because the unit of velocity(v) is m/s and the unit of time,... View Article

From the given v – t graph (Fig.), it can be inferred that the object is (a) in uniform motion (b) at rest (c) in non-uniform motion (d) moving with uniform acceleration

Answer: (a) in uniform motion From the above-given graph, it is clear that velocity of the object remains constant throughout hence the object... View Article

If the displacement of an object is proportional to square of time, then the object moves with (a) uniform velocity (b) uniform acceleration (c) increasing acceleration (d) decreasing acceleration

Answer: (b) uniform acceleration Displacement is defined as the change in position of an object. It is a vector quantity and has a direction and... View Article

The numerical ratio of displacement to distance for a moving object is (a) always less than 1 (b) always equal to 1 (c) always more than 1 (d) equal or less than 1

Answer: The magnitude of displacement is defined as the shortest distance between the initial and final position of the object. Magnitude of... View Article

A body is thrown vertically upward with velocity u, the greatest height h to which it will rise is, (a) u/g (b) u2/2g (c) u2/g (d) u/2g

Answer: (b) u2/2g At the greatest height h, a body thrown vertically upward with velocity u will have a final velocity (v) zero. Given parameters... View Article

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