Time (h) 0 1 2 3 4 5
Displacement (km) 0 40 80 120 160 200
The following table gives distance moved by a bus at corresponding time intervals. Draw a graph showing distance covered by the bus with time choosing a suitable
scale.
From the graph, calculate, the speed of the bus during the following time interval 2 to 4 hours
• Mark the point corresponding to time 2 hours on the graph as A and that corresponding to 4
hours as B on the graph.
• Shade the area covered between distance-time graph and time axis which is used to calculate
the speed of the body.
• Interpret the kind of motion from the shape of the graph.
hello friend take time and solve this question on graph and get a chance to be brainlist and i will follow the 5 correct answers and also transfer 100points to first correct answer from my account
Answers
Answer:
Answer:
Here, Side of the given square field = 10m
so, perimeter of a square = 4*side = 10 m * 4 = 40 m
Farmer takes 40 s to move along the boundary.
Displacement after 2 minutes 20 s = 2 * 60 s + 20 s = 140 seconds
since in 40 s farmer moves 40 m
Therefore, in 1s the distance covered by farmer = 40 / 40 m = 1m
Therefore, in 140s distance covered by farmer = 1 � 140 m = 140 m. Now, number of rotation to cover 140 along the boundary= Total Distance / Perimeter
= 140 m / 40 m = 3.5 round
Thus, after 3.5 round farmer will at point C of the field.
Thus, after 2 min 20 seconds the displacement of farmer will be equal to 14.14 m north east from initial position.
3. Which of the following is true for displacement?
(a) It cannot be zero.
(b) Its magnitude is greater than the distance travelled by the object.
Answer: None of the above statements is actually true for displacement.
First statement is completely false because displacement can be zero in case of a circular path. Second statement is also false because displacement is less than or equal to the distance travelled by the object in case of motion in opposite direction.
INTEXT QUESTIONS Pg 102
1. Distinguish between speed and velocity.
Answer:
Speed Velocity
Speed is the distance travelled by an object in a given interval of time. Velocity is the displacement shown by an object in a given interval of time.
Speed = Distance / Time Velocity = Displacement / Time
Speed is scalar quantity and has only magnitude. Velocity is vector quantity and has both magnitude and direction.
2. Under what condition(s) is the magnitude of average velocity of an object equal to its average speed?
Answer: The magnitude of average velocity of an object is equal to its average speed, only in one condition when an object is moving in a straight line.
3. What does the odometer of an automobile measure?
Answer: The odometer of an automobile measures the distance covered by a vehicle or an automobile.
4. What does the path of an object look like when it is in uniform motion?
Answer: An object with uniform motion has a straight line path.
5. During an experiment, a signal from a spaceship reached the ground station in five minutes. What was the distance of the spaceship from the ground station? The signal travels at the speed of light, that is, 3 × 108 m s-1.
Answer
Speed= 3 × 108 m s-1
Time= 5 min = 5 *60 = 300 seconds.
Distance= Speed * Time
Distance= 3 * 108 m s-1 * 300 secs. = 9 x 1010m
INTEXT QUESTIONS Pg 103
1. When will you say a body is in (i) uniform acceleration? (ii) Non-uniform acceleration?
Answer:
(i) A body is said to be in uniform acceleration if it travels in a straight line and its velocity increases or decreases by equal amounts in equal time intervals.
(ii) A body is said to be in non-uniform acceleration if the rate of change of its velocity is not constant, that is differs in different time intervals.
2. A bus decreases its speed from 80 km h-1 to 60 km h-1 in 5 s. Find the acceleration of the bus.
Answer:
3. A train starting from a railway station and moving with uniform acceleration attains a speed 40 km h-1 in 10 minutes. Find its acceleration.
Answer:
INTEXT QUESTIONS Pg 100
1. What is the nature of the distance - 'time graphs for uniform and non-uniform motion of an object?
Answer: When the motion is uniform, the distance time graph is a straight line with a slope.
When the motion is non-uniform, the distance time graph is not a straight line. It can be any kind of curve.
2. What can you say about the motion of an object whose distance - time graph is a straight line parallel to the time axis?
Answer: If distance time graph is a straight line parallel to the time axis, the body is said to be at rest.
3. What can you say about the motion of an object if its speed - ‘time graph is a straight line parallel to the time axis?
Answer: If speed time graph is a straight line parallel to the time axis, the object is said to be moving uniformly.
4. What is the quantity which is measured by the area occupied below the velocity -time graph?
Answer: The area under the velocity-time graph gives the distance covered by an object.
INTEXT QUESTIONS Pg 109
1. A bus starting from rest moves with a uniform acceleration of 0.1 m s-2 for 2 minutes. Find (a) the speed acquired, (b) the distance travelled.
Answer: Initial speed of the bus, u= 0 m/s
Acceleration, a = 0.1 m/s2
Time taken, t = 2 minutes = 120 s
(a) v= u + at
v= 0 + 0×1 × 120
v= 12 ms-1
(b) According to the third equation of motion, v2 - u2= 2as
s is the distance covered by the bus
(12)2 - (0)2= 2(0.1) s
s = 720 m
Speed acquired finally by the bus is 12 m/s.
Distance travelled by the bus is 720 m.
INTEXT QUESTIONS Pg 110
Explanation: