1.What is the momentum of a man of mass 75 kg when he walks with a velocity of 2m/s?
2. A man pushes a box of mass 50 kg with a force of 80 N. what will be the acceleration of the box?
What would be the acceleration if the force were doubled?
3. A motorcycle is moving with a velocity of 90km/hr and takes 5 sec to stop after brakes are applied.
Calculate the force exerted by the brakes on the motorcycle if its mass alongwith the rider is 200kg.
4. State Newton’s second law of motion.
5. Derive F= m*a from Newtons second law of motion
6. A truck of starts from rest and rolls down a hill with a constant acceleration. It travels a distance of
400m in 20 sec. Find the force acting on it if its mass is 7 metric tonnes ( Hint 1 metric tonne =
1000Kg)
7. A stone is thrown with a velocity of 20 m/s across the frozensurface of a lake and comes to rest
after travelling a distance of 50m. What is the force of friction between the stone and the ice?
please tell as soon as possible full explanation
only those people answer who know
Answers
Explanation:
1) here: the mass of the man = 75kg
Man is moving with the uniform velocity v= 2m/s
Momentum, p=mv
= 75* 2
=159 kg m/ s
2)Force=mass*acceleration
acceleration=force/mass
acceleration=80/50=1.6m/s
when mass is halved
acceleration=80/25=3.2m/s
if mass is halved then acceleration is doubled
3)initial velocity(u) = 90 km/s = 25 m/s
time (t) = 5 sec
mass (m) = 200 kg
final velocity (v) = 0 m/s
v = u + at
0 = 25 + a * 5
-25 = 5 a
-5 = a
Therefore acceleration = -5m/s²
Force = mass * acceleration
F = 200*-5
F = -1000 N
4)Newtons second law of motion states that the rate of change of momentum of an object is proportional to the applied external force and takes place in the direction in which external force acts
5) i attached a picture above
6)The truck starts from rest, so initial velocity = 0
Distance travelled = 400 m
Time taken = 20 s
We know the equation of motion, S = ut + ½ at2
400 = 0 + ½ a * (20)2
a = 2 m/s2
Now, mass = 7 metric tonnes
= 7 * 1000
= 7000 kg
So force = mass * acceleration
F = 7000 * 2
= 14000 N
7)Mass = 1 kg, Initial Velocity = 20 m/s and Distance travelled = 50 m. Since the object comes to rest at the end, the final velocity is 0 m/s. => Acceleration = ? Hence the frictional force is -4 N
Answer:
Hey dear here is your answer!!!!!
Firstly we have to find acceleration for finding force so ;
Given :- v = 0
t = 10 sec
u = 25m/s
Acceleration = v-u/t
a = -2.5 m/s^2
Since acceleration is negative it means it is retarding.
Force = mass × acceleration
= 200 × (-2.5 )
= - 500 N
It means it is applied on the opposite direction .
Explanation: