A ball is thrown vertically downward with a velocity of 20 m/s from the top of a tower. It hits the ground after some time with the velocity of 80 m/s . The height of the tower is: $(\mathrm{g}=10<mspace\; width="1em"></mspace>\mathrm{m}/{\mathrm{s}}^2)$

1. 340 m

2. 320 m

3. 300 m

4. 360 m

A bullet moving at speed of 10 m/s hits the wooden plank and is stopped when it penetrates the plank 50 cm deep. What is the retardation of bullet? (Assuming constant retardation)
1. 100 m/s²
2. 1000 m/s²
3. 50 m/s²
4. 250 m/s²

A particle has initial velocity \(\left(2 \hat{i} + 3 \hat{j}\right)\) and acceleration \(\left(0 . 3 \hat{i} + 0 . 2 \hat{j}\right)\). The magnitude of velocity after \(10\) s will be:

A stone is thrown vertically downwards with an initial velocity of \(40\) m/s from the top of a building. If it reaches the ground with a velocity of \(60\) m/s, then the height of the building is: (take \(g=10\) m/s²)

A ball of mass 2 kg and another of mass 4 kg are dropped together from a 60 feet tall building. After a fall of 30 feet each towards the earth, their respective kinetic energies will be in the ratio of:

1. 1: 4

2. 1: 2

3. 1: $\sqrt{2}$

4. $\sqrt{2}$ :1

The displacement of a particle is given by $y=a+bt+c{t}^2-d{t}^4$. The initial velocity and acceleration are respectively 

1. $b,-4d$

2. $-b,2c$

3. $b,2c$

4. $2c,-4d$ 

A particle starts from origin \(O\) from rest and moves with a uniform acceleration along the positive \(x\text-\)axis. Identify all figures that correctly represent the motion qualitatively.
(\(a=\) acceleration, \(v=\) velocity, \(x=\) displacement, \(t=\) time)

(A)		(B)
(C)		(D)