Ask a Doubt
Request a call back

Join NOW to get access to exclusive study material for best results

CBSE Class 9 Answered

An object starts from rest and travels 20m in first 2 s and 160 m in 4 s . Find its velocity 7 s after the start .
Asked by asyadav1230 | 20 Dec, 2022, 07:17: AM
Expert Answer
u = 0, 
distance travelled in first 2s (s) = 20 m 
distance travelled in 4s (S) = 160 m 
 
s = ut + 1/at2 
20 = 1/2 a (2)2 
a = 10 m/s2 
Thus, velocity at the end of 2s is 
v = u + at 
v = 0 + 10 x 2 = 20 m/s 
 
S = ut + 1/2 at2 
160 = 20 x 4 + 1/2 a' (4)2 
80 = 8a'
a' = 10 m/s2 
Now after 7s from start the velocity of object will be, 
v = 0 + 10 x 7 = 70 m/s 
Answered by Shiwani Sawant | 20 Dec, 2022, 09:14: AM

Concept Videos

Multiple Choice Questions Practice Test Subjective Questions Webinar Subjective Questions Pre Board Assessment
Answered Unanswered My Questions My Answers
CBSE 9 - Physics
An object starts from rest and travels 20m in first 2 s and 160 m in 4 s . Find its velocity 7 s after the start .
Asked by asyadav1230 | 20 Dec, 2022, 07:17: AM
ANSWERED BY EXPERT
CBSE 9 - Physics
Two points A and B are located on the floor of a room 30cm and 20cm away from a wall. The distance between the points parallel to the wall is 50cm. An insect is at moving on the floor at 5cm/s. It has to first reach a point C on the wall and then reach B such that AC and BC make equal angles with Normal to the wall at C. The time taken for this  motion will be
Asked by rajesh kumar | 21 Oct, 2022, 08:15: PM
ANSWERED BY EXPERT
CBSE 9 - Physics
A student starts with a velocity 40 km/hr for school at 4 km away from his house. Due to closing of school he returns soon to his house with a velocity of 60km/hr.His average velocity will be.
Asked by manognabandla2004 | 08 Sep, 2022, 07:55: PM
ANSWERED BY EXPERT
CBSE 9 - Physics
a body goes from a to b with a velocity of 20ms and come back from b to a the average velocity of 30ms the average velocity of the body during the whole journey is
Asked by ayushyadav70303 | 12 Jul, 2022, 07:32: AM
ANSWERED BY EXPERT
CBSE 9 - Physics
what is vector quantities
Asked by drnaimansari2222 | 11 Jun, 2022, 04:28: PM
ANSWERED BY EXPERT
CBSE 9 - Physics
ar Covers 50km in 15 mins and then covers 65km in next 15 mins. calculate it's average speed​
Asked by suzanesharma307 | 30 May, 2022, 11:03: PM
ANSWERED BY EXPERT
CBSE 9 - Physics
a car is moving with the acceleration 2m/s from rest find the distance traveled by the car in 10th second
Asked by syedmehdiali543 | 17 Apr, 2022, 04:01: PM
ANSWERED BY EXPERT
CBSE 9 - Physics
A car travells 33 km south 13 km west and 14 km north in half an hour calculate the average velocity   
Asked by Out81874 | 23 Dec, 2021, 09:56: PM
ANSWERED BY EXPERT
CBSE 9 - Physics
briefly explain different type of motions
Asked by devanandsahu800 | 21 Dec, 2021, 10:52: AM
ANSWERED BY EXPERT
CBSE 9 - Physics
in 12 minute a car whose speed is 35km/hr travel with a distance of   
Asked by tanya.tyagi010 | 14 Oct, 2021, 11:26: PM
ANSWERED BY EXPERT
My Class Videos Tests ₹ Plans Ask a Doubt