Answer:
The speed is 
Explanation:
Electric field magnitude (E) and electric force magnitude (F) are related by the equation

with q the charge of the proton (
). Because between parallel plates electric field is almost constant, electric force is constant too:

because electric force is constant, then by Newton's second law acceleration (a) is constant too, it is:

with m the mass of the proton (
):

Now with this constant acceleration we can use the kinematic equation

with v the final speed,
the initial velocity that is zero (because proton starts at rest) and d is the distance between the plates, so:

A constant velocity implies the two forces must be equal and opposite.
Friction acts horizontal to the ground, therefore we must find the force applied to the sled rope that acts horizontal to the ground.
Do this by resolving:
Force = 80cos53
The force opposing this is equal, and so also = 80cos53 = 48 N (2 sig. fig.)
The period of a simple pendulum is given by:

where L is the pendulum length, and g is the gravitational acceleration of the planet. Re-arranging the formula, we get:

(1)
We already know the length of the pendulum, L=1.38 m, however we need to find its period of oscillation.
We know it makes N=441 oscillations in t=1090 s, therefore its frequency is

And its period is the reciprocal of its frequency:

So now we can use eq.(1) to find the gravitational acceleration of the planet:
Happy Holidays!
Recall that:
Impulse = Change in Momentum = mass × change in velocity
Since both cars are identical and have the same initial velocity of 60 mph, them breaking to a stop means that they both experience the same change in velocity.
Thus, both of the cars' impulses are equal.