Question

9. A car falls off a ledge and drops to the ground in 0.5 s. Let g = 10 m s–2 (for simplifying the

calculations). (i) What is its speed on striking the ground? (ii) What is its average speed during the 0.5 s?

(iii) How high is the ledge from the ground?
answer fast ​

Answer 1

Answer:

Given,

time taken=0.5s

g=10ms

−2

As the car is under free fall, the initial speed is zero.

(a) Under free fall,

u=0

a=g

v=u+at

v=0+10×0.5

v=5ms

−1

(b) Average speed =

2

u+v

=

2

0+5

=2.5ms

−1

(c) From newton's equation of motion, As u=0,

h=ut+

2

1

gt

2

When h is the height, t is the time of free fall, g is the acceleration due to gravity. Putting the values in the above equation, we get

h=

2

1

×10×(0.5)

2

=5×0.25=1.25m

Solve any question of Motion in a Straight Lin

Answer 2

Answer:

Given,

time taken=0.5s

g=10ms−2

As the car is under free fall, the initial speed is zero.

(a) Under free fall, 

u=0 

a=g

v=u+at

v=0+10×0.5

v=5ms−1

(b) Average speed = 2u+v=20+5=2.5ms−1

(c) From newton's equation of motion, As u=0,

h=ut+21gt2

When h is the height, t is the time of free fall, g is the acceleration due to gravity. Putting the values in the above equation, we get

h=21×10×(0.5)2=5×0.25=1.25m

Explanation:

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