Answer:
3360 N
Explanation:
In a first-class lever, the effort force and load force are on opposite sides of the fulcrum.
The lever is 5 m long. The load force is 1.50 m from the fulcrum, so the effort force must be 3.50 m from the fulcrum.
The torques are equal:
Fr = Fr
(1440 N) (3.5 m) = F (1.5 m)
F = 3360 N
The average force applied to the ball= 106.7 N
Explanation:
Force is given by
f= ΔP/t
ΔP= change in momentum= m Vf- m Vi
m= mass =0.2 kg
Vf= final velocity= 12 m/s
Vi=initial velocity= -20 m/s ( negative because it is going towards the wall which is treated as negative axis)
t= time= 60 ms= 0.06 s
now ΔP= 0.2 [ 12-(-20)]
ΔP=0.2 (32)=6.4 kg m/s
now force F= ΔP/t
F= 6.4/0.06
F=106.7 N
Answer:
Because it has more mass
Explanation:
To understand this, think about the equation of kinetic energy
KE = 
m 
Kinetic energy depends on both the velocity (v) as well as the mass (m).
Because a lorry is bigger and heavier than a car, it will have more mass. With more mass, at the same velocity the lorry with have more kinetic energy.
Answer:
The statement is true: velocity and acceleration have opposite directions in the interval of braking.
Explanation:
Let's say we have a velocity 
.
The acceleration 
is the rate of change of the velocity 
. This means that if is <em>increasing during</em> time, then must be positive. But if is <em>decreasing over</em> time, then will be negative (even though the velocity is positive).
Mathematically:
decreases ⇒
⇒
.
Example:
