Time

Q.

A body travels 200 cm in the first two seconds and 220 cm in the next four seconds. The velocity at the end of seventh second from start is

1. 10 cm/s

2. 15 cm/s

3. 20 cm/s

4. 5 cm/s

Q. The equations of motion are applicable in which of the following conditions?

1. Non-uniform acceleration
2. Continuously increasing acceleration
3. Continuously decreasing acceleration
4. Uniform acceleration

Q.

A body released from the top of a tower falls through half the height of the tower in $3s$. It will reach the ground after nearly

1. $3.5s$

2. $4.24s$

3. $4.71s$

4. $6s$

Q.

Can the equations of motion be used in a situation where acceleration varies with time? Can they be used when acceleration is zero?

Q.

Give reason: The motion of satellites around planets is considered as an accelerated motion.

Q.

Look at the speed-time graph of a car given below and answer the question :

What type of motion is represented by AB?

Q. Two cars start from the same point simultaneously and in the same direction. The first car travels at $40$ km/h, and the speed of the second car is $125$ per cent of the speed of the first car. Thirty minutes later a third car starts from the same point and in the same direction. It overtakes the second car $1.5$ h later than it overtook the first car. What is the speed of the third car?

Q.

A stone thrown vertically upward rises to a height of $29.34m$ on the surface of the Moon. If the acceleration due to gravity on the surface of the Moon is $1.63m{s}^{-2}$. Calculate the time taken to gain the maximum height.

Q. Add the following.
$5hr40$ min $23$ sec and $1hr35$ min $56$ sec

Q. Curie is the unit of

1. radio-activity
2. half-life
3. decay constant
4. average life