Answer: 75.8 %
Explanation:
Half-life of tritium= 12.33 years
First we have to calculate the rate constant, we use the formula :
Now we have to calculate the age of the sample:
Expression for rate law for first order kinetics is given by:
where,
k = rate constant =
t = age of sample = 5 years
a = let initial amount of the reactant = 100 g
a - x = amount left after decay process = a g
Now put all the given values in above equation, we get
Thus 75.8 percentage of a sample will remain after 5 years have passed.
Answer:
(a) It will take 12.82 sec to come into rest
(b) After calculation distance is 737.15 m which is less than 800 m so jet can land on the island
Explanation:
(a) When the jet lands at the ground its velocity is 115 m/sec
So initial velocity u = 0 m/sec
Finally jet will stop so its final velocity will be zero v = 0 m/sec
Maximum acceleration
So minimum time,
So
t = 12.82 sec
(b) Average speed
Distance traveled in 12.82 sec =
As this distance is less than 800 m so jet can land on the island
Answer:
A. The ball has a negative acceleration on the way up and a positive acceleration on the way down.
Explanation:
- When a ball is thrown up vertically then the acceleration due to gravity always acts in a direction towards the center of the earth. So here when an object is thrown vertically upwards then the acceleration due to gravity acting in a downward direction which is opposite to the direction of motion of the object hence taken as negative with respect to the displacement.
- When the ball reaches at the top height its speed becomes zero and then it returns back towards the earth. While coming down the direction of the object's displacement is same as the direction of acceleration due to gravity.