1. A girl of mass 50 kg jumps with a horizontal velocity of 5 ms 'on to a stationary cart
with frictionless wheels. The mass of the cart is 2 kg. What is her velocity as the cart
starts moving?
2. A bullet of mass 50 g is horizontally fired from a pistol of mass 2 kg with a horizontal
velocity of 250 m/s. Calculate the recoil velocity of the pistol.
3. (a) It is easier to stop a tennis ball than a cricket ball moving with the same speed.
Why?
(b) A constant force acts on an object of 5 kg for a period of 2 s. It increases the
velocity of the object from 3 m/s to 7 m/s. Find the magnitude of the applied force.
Now, if the force were applied for a period of 5 s, what would be the final velocity of
the object?
4. (a)Derive the law of conservation of momentum.
(b)Two objects each of mass 1.5kg, are moving in the same straight line but in
opposite directions. The velocity of each object is 2.5m/s before the collision during
which they stick together. What will be the velocity of the combined object after
collision?
5. Represent the following graphically
(a) Momentum versus velocity when mass is fixed.
(b) Momentum versus mass when velocity is constant.
Plss answer fast. It's urgent!
I swear I will mark you as BRAINLIEST.
Answers
Answer:
1} 4.65 m/sec
2} -1.5m/sec
4} 3×v=3.75−3.75
Explanation:
1} No external force=momentum is constant
momentum of girl =40×5=200kg-m/sec
momentum of girl and cart= total momentum of girl +total momentum of cart
200+0=200kg m/sec
speed =200/{40+3}
= 4.65m/sec
2}Let the direction in which the bullet is fired be positive.
Therefore,
Mass of Bullet(m)=20 grams=0.02 kg
Mass of Pistol(M)=2 kg
Initial Velocity of Bullet(u)=0 m/s
Initial Velocity of Pistol(U)=0 m/s
Final Velocity of Bullet(v)=150 m/s
Final Velocity of Pistol(V)= Recoil Velocity of Bullet = ?
According to the Law of Conservation of Momentum,
mu + MU = mv + MV
(0.02)(0) + (2)(0) = (0.02)(150) + (2)(V)
0 + 0 = 3 + 2V
-3/2 = V
V = -1.5 m/s
Therefore, the recoil velocity of the pistol will be 1.5 m/s in the opposite direction.(As the sign is negative)
4}Let the objects be A and B moving from opposite directions in the same straight line.
∴ Initial momentum of A =m×v
=1.5×2.5=3.75kgms
−1
Also, initial momentum of B
=m×v=1.5×(−2.5)=−3.75kgms
−1
If v is the velocity of the objects after collision, then final momentum after collision =3×v
Using the law of conservation of momentum, final momentum of A and B =
initial momentum of A + initial momentum of B
or 3×v=3.75−3.75
or 3×v=0 or v=0