Question

a ball is dropped from a diff. find (a) its speed 2 second after it is dropped (b) its speed when it has fallen through 78.4m (c) the time taken is falling through 78.4.​

Answer 1

Answer:

Velocity after two seconds

v=u+gt

v=0+9.8×2

v=19.6m/s

Velocity when a ball has fallen through 78.4m is given by

v  

2

−u  

2

=2gh

v  

2

−0=2×9.8×78.4

v  

2

=1536.64

v=39.2m/s

Let time taken in falling through 78.4m be ts.

h=ut+  

2

1

​  

gt  

2

 

78.4=0×t+  

2

1

​  

×9.8×t  

2

 

t  

2

=  

4.9

78.4

​  

 

t  

2

=16

t=4s

Thus time taken in falling through 78.4m is 4s.

Explanation:

Answer 2

Explanation:

answer for A is 19.6m/s

B is √1396.64

C is √78.4/4.9